The changes will temporarily alter the look and feel of Twitter. The company will essentially give users a timeout, for example, before they can hit the button to retweet a post from another account. And if users try to share content that Twitter has flagged as false, a notice will warn them that they are about to share inaccurate information.

Twitter also said it would add a label to claims about who won the election until it has been called by authoritative sources…

In recent weeks, Twitter has already added warning labels to lies posted by elected officials — flagging several of Mr. Trump’s tweets — and has cracked down on photos and videos that had been manipulated to deceive viewers. The company has not accepted political advertising for nearly a year.

Most of the latest changes will happen on Oct. 20 and will be temporary, Twitter said. Labels warning users against sharing false information will begin to appear next week. The company plans to wait until the result of the presidential election is clear before turning the features back on.