The United States and Soviet Union might decide to take "the easy way out" of fundamental arms control conflicts by negotiating "cosmetic agreements" in coming months to extend and slightly expand the SALT II treaty, according to Brent Scowcroft, a leading nongovernmental expert on arms issues.

Scowcroft, speaking at a breakfast meeting with reporters, said such a limited U.S.-Soviet agreement was an alternative to "very protracted" negotiations that would be required to deal with the U.S. Strategic Defense Initiative, or "Star Wars" plan, as well as deep cuts in offensive forces.

Proposals to seek limited agreements through relatively speedy negotiations are under consideration in the administration, officials said, as policy-making continues in preparation for the Jan. 7-8 meeting in Geneva between Secretary of State George P. Shultz and Soviet Foreign Minister Andrei A. Gromyko.

Scowcroft, a retired Air Force general who was national security adviser to President Gerald R. Ford and chairman of the recent special commission on the MX missile, cautioned, "I don't relly really think you ought to expect much" from the Shultz-Gromyko meeting.

About the maximum that could come of it, he said, is a "sorting out" on a procedural level of how to deal with the three categories of issues the two sides agreed to discuss: strategic offensive arms, intermediate-range arms and space weapons.

The Shultz-Gromyko meeting should be considered "an initial contact after a period of estrangement" in arms control, said Scowcroft, who expressed dismay at being told that NBC News anchorman Tom Brokaw is going to broadcast from Geneva during the session. Too much pressure for quick progress resulting from soaring press and public expectations could complicate the discussions, Scowcroft said.

As the meeting approaches, he said, the Soviets "want to get rid of space defense programs without giving anything for it" and probably will insist that the United States "show its seriousness" by agreeing to halt space testing and making other concessions.

On the other hand, the "inclination" of the U.S. adminstration is not to put the space defense program on the bargaining table, he said.

To negotiate large-scale changes in offensive nuclear forces, it will be necessary to reconcile "those fairly extreme positions" in the space area, Scowcroft said. He added this could be "very protracted."

The alternative to such major strategic tradeoffs, in Scowcroft's view, would be "cosmetic agreements" (which he referred to at another point as "a modest agreement") to extend and improve the SALT II treaty, probably under another name for political acceptability in Washington. The 1979 treaty, which has not been ratified by the United States, is due to expire at the end of 1985. Both sides have agreed not to undercut it if the other party does the same.

Among the elements of such a limited pact, he said, would be designation of warheads rather than missile launchers as the standard of accounting under the treaty and some reduction of numbers of ballistic missiles allowed on each side. Proposals by both the United States and the Soviet Union in the strategic arms reduction talks (START) moved in this direction before the bargaining was put into limbo by the Soviets a year ago this month.

Such a pact would be attractive "if you want to signal a changed U.S.-Soviet relationship" and might be possible without tackling the tough issue of strategic defense, Scowcroft said.