I've recently been getting back to the gym and getting my diet cleaned up (for mental health reasons above any other), and as a result I've lost about 30 pounds in 3 months and gained some muscle along the way - far better than I thought was possible at my age.
I also saw a post on Reddit of scans of the legs of 2 70-year-olds; one active and the other sedentary. The active one was almost all muscle while the sedentary one was riddled with fat.
There's no secret; it's diet and exercise, but obviously it isn't easy either. If ozempic can help with the one, then that's a big bonus.