After a dip during the pandemic, enrollment has risen for three straight years. Elite universities continue to have vastly more applicants than seats.

Dual credit can help students be better prepared for college and avoid debt. But some worry about watered-down curriculums and students ending up with credits that selective colleges might not accept.

Katie Keith, a director at Georgetown University’s O’Neill Institute for National and Global Health Law, said the administration was sending mixed messages, on one hand “talking about its ...