The entry of one of America's best-known coporate giants last week in a real estate world inhabited largely by Lilliputians has been met with trepidation by some local brokers and with bravado by others.

The beleaguered home seller or buyer, meanwhile, may find that the acquisition of Coldwell, Banker & Co. by Sears Roebuck & Co. means a new kind of real estate department store around the corner, a larger one that includes a well-stocked "creative financing" counter.

That, at least, is part of what Sears, the world's biggest retailer, had in mind when it agreed to buy the California-based Coldwell Banker, the country's largest independent real estate brokerage. With that acquisition and its purchase the same week of Dean Witter Reynolds, a Wall Street brokerage firm, Sears significantly expanded its already extensive financial services holdings, opening up a wide range of possibilities for combined financial operations.

Merrill Lynch started a trend in this direction when it began buying insurance companies and real estate firms, including the purchase of Washington's Chris Coile Realty early last year. Some smaller independents already began to fear then that they might be crowded out of the market.

"The influx of the giants into the industry is very frightening," said James Bugg, executive director of the newly formed Certified Associates in Real Estate. CARE is a loose association of independent brokers created earlier this year in the hopes of finding strength in unity. It began in Washington, and 12 other chapters have been started in other cities.

"The reason we organized was because we felt the threat of the Merrill Lynches and Coldwell Bankers and the influx of Wall Street" into the real estate industry, Bugg said. The group is planning to start local television advertising on Monday, but Bugg's enthusiasm for that campaign is tempered by the news that a formidable corporate competitor now is backed by a conglomerate with even more resources.

"How can the independents compete with the many services that a Sears can offer?" he asked.

Several other local real estate experts predict that a Coldwell Banker with Sears' vast financial resources behind it is bound to make greater inroads into the real estate markets both nationally and in the Washington area, where it first entered the residential real estate market in 1976 with its acquisition of the Alexandria-based Routh Robbins firm.

"I see a big, successful, aggressive Coldwell Banker branch getting bigger, more aggressive and more successful," said Justin Hinders, a local commercial broker.

Joseph Moravec of the Leggat, McCall & Werner brokerage firm said that Coldwell Banker "already constituted a significant challenge to the more traditional regional real estate brokers," such as his own firm, but that the Sears backing will provide an even greater competitive edge.

But the other major real estate conglomerate, Merrill Lynch Realty-Chris Coile, says it invites the added competition.

"I think the acquisition is a terrific thing," said Merrill Lynch-Chris Coile President William Barrett. "The real estate industry is finally becoming a business and being run like any other business."

The corporate backing will only add to the professionalism of the industry, Barrett said, and besides, "good competitors keep us on our toes."

Smaller firms argued, however, that rather than getting more professional the industry is becoming less personal.

The consolidation of all real estate services, particularly financing, under one roof may be the greatest change the home buyer or seller will find because of the acquisition.

"Real one-stop shopping" for the home buyer is how Kenneth Tuchtan of the Routh Robbins residential sales division of Coldwell Banker describes the future of the company. While the firm currently offers a number of financial services, including VA and FHA loans and mortgage insurance, it does not now offer the "new exotic instruments" that many home buyers require to buy a house, Tuchtan said. With the acquisition, the company will be able to offer adjustable-rate mortgages, for example, he said.

Coldwell Banker will be under Sears' Seraco Group, which includes a large California savings and loan association and is involved in shopping centers, commercial real estate and mortgage insurance. It is expected that Coldwell Banker will keep its own name, and Sears officials have said its operating philosophy will be kept intact.

Sears had $25.2 billion in sales last year, 859 retail stores and 25 million credit card customers nationwide. Coldwell Banker, based in California, but with offices throughout the country, had revenues of $345 million last year. Sears agreed to buy the real estate company for $179 million in cash and Sears stock.

Despite the corporate resources, some local real estate brokers say Sears will not be willing or able to do much about lowering interest rates on its loans, and that, they say, is the one way to increase home sales in today's depressed market.

"Will Sears be able to make mortgage loans at rates lower than anyone else? Why would they?" asked William Ellis, vice president and director of residential sales for Shannon & Luchs Realtors, a large locally owned real estate firm. "There's no way they're going to lend money out at a lower return than they can get on the street."

"That's what happened to Merrill Lynch. After the initial shocks, they just functioned like any other broker. Their mortgage department is in competition with everyone else's," Ellis added.

William Stuart III, president of Stuart & Maury Inc., predicted the kind of local, personalized service his firm prides itself on will win out over the financial advantages a Sears subsidiary has.

"I think it's the old personal service that will count," particularly where the head of the company is available to the customer, Stuart said. "I'm not the least bit intimidated."

But others here obviously are, by the intractably depressed market as well as by the corporate competition, and the number grows of real estate firms taking shelter in franchises, which band independent agents together under one name nationwide. The larger firms say they are getting more requests than ever from smaller agents wanting to be bought out.

"This is part of the demise of the independent, locally owned, multibranch real estate firm," predicted one local real estate expert. "Soon they will all be forced to merge into others, gobbled up by giants or will go out of business."

One exception that this analyst and others noted, however, were firms that specialize, such as those that operate almost exclusively in Georgetown property.

But some smaller brokers already have succumbed, unable to hang on any longer in a market that has been in a slump for more than three years. At CARE, for example, the group announced earlier this year that it had about 60 affiliates in the Washington area. But already this year, six of these members have gone out of business, executive director Bugg said.

At this point, the only hope for survival Bugg sees for the individualistic independents his group represents is combined strength.

The 13 chapters of CARE "are like the 13 original states," he said. "The Maryland Catholics didn't have much in common with the New England Protestants except the common enemy of Mother England. But the only way we can fight back is if we fight together."