California officials have been working for months on a plan to “Trump proof” the state’s leading edge environmental and climate policies, in the event that former President Donald J. Trump returns to White House and follows through on his promise to gut them.

Whether California succeeds could affect more than a dozen other states that follow its emissions rules, and could have global impact because the state’s market muscle compels auto makers and other companies to conform to California standards.

The strategy now being crafted in Sacramento includes lawsuits designed to reach wide-ranging settlements with industries that generate greenhouse gases, and new rules and laws that rely on state authority and would be beyond the reach of the administration.

Mr. Trump, who considers climate change a “hoax,” has promised to weaken every major federal climate regulation, as he did in his first term.

But he is also expected to try to blow up California’s climate policies, which have set the pace for the rest of the nation and the world. The state is requiring about three-quarters of new trucks sold there after 2035 to be zero emissions. And in a request that is pending, California wants permission from the Biden administration to enact one of the most ambitious climate rules of any nation: a ban on the sale of new gas-powered passenger vehicles in the state after 2035.

Both rules are far tougher than federal policy and could have influence beyond the United States, given California’s standing as the world’s fifth-largest economy. China and the European Union have already adopted parts of California’s car and truck tailpipe emissions reduction programs.