One main conclusion: The social constraints that were once a barrier to voting Republican have eroded, in large part because the strong economy during much of Mr. Trump’s term caused many Latino voters to give the party a second look.

“You had a set of Latino voters who weren’t especially partisan and who had seen it as socially unacceptable to vote for Trump in 2016,” said Carlos Odio of Democratic-aligned Equis Research, which conducted surveys and focus groups to understand the shift. “‘My friends and family will be mad at me if I do this.’ You need a justification to do it.”

“The economy, the issue on which they trusted Trump, unlocked the door to embracing him,” Mr. Odio said.

At the same time, many Latino voters came to view the Democratic Party as untethered from their top concerns—unsupportive of law enforcement, too lax on border security and too focused on racial disparities, said Ruy Teixeira, a demographics expert and co-editor of The Liberal Patriot newsletter. Among other things, this brought the GOP new votes from Hispanic voters who have a conservative bent but hadn’t acted on it, he said.