Since her victories on Tuesday, Mrs. Clinton has met with advisers at her home in Chappaqua, N.Y., to discuss taking on Mr. Trump. A playbook is beginning to come together.

On the debate stage, Mrs. Clinton will not respond in kind to personal attacks: No jokes about Mr. Trump’s hair or the size of his hands. When Mr. Trump’s comments dominate the news, her campaign plans to stick to its message, even if it means being momentarily eclipsed. And when Mr. Trump accuses Mrs. Clinton of playing the woman’s card, Mrs. Clinton will pivot to issues like equal pay for women, paid family and medical leave and raising the minimum wage.

“This can’t be a tit for tat on comedic insults,” said Hilary Rosen, a Democratic strategist. But, she added, without the right pushback, Mr. Trump’s attacks “could have a corrosive impact, and that’s what the campaign is thinking hard about.”

Still, pushing back against Mr. Trump is unlikely to go unanswered. In January, after Mrs. Clinton accused him of being sexist, he warned that Bill Clinton’s sexual indiscretions would be fair game, accused Mrs. Clinton of impugning the reputations of women who accused her husband of sexual indiscretions, then boasted that Mrs. Clinton had been intimidated into dropping the subject.

Aides to Mr. Trump, three of whom insisted on anonymity to discuss the campaign’s internal deliberations, suggested he would likely return to that line of attack as his campaign prepares for a fall contest with Mrs. Clinton.