Cagrilintide (paired with semaglutide) and retatrutide are the next wave, though I'm not aware of any research for either indicating an increase in muscle mass.

My understanding of the literature is that there's nothing special about semaglutide or tirzepatide that promote muscle loss - it's just people who lose weight based purely on diet tend to also lose muscle mass. Even bodybuilders lose some muscle mass when cutting.

It's up to the individual to increase their protein intake and exercise, the same way they would in any caloric deficit.