general prescription these days for Hypertrophy is 10 sets per muscle group per week 0-3 RIR.
The title says they are focused on improving body composition which is boosting lean mass, lowering of fat mass which kinda seems achieved best by focusing on Hypertrophy and fat loss?
The only reason I mention it is because I often see people, especially men, assume getting bigger is the main focus of getting stronger and healthier. But a more holistic approach including stretching, functional strength excercises, cardio and balance training is perhaps more important
And on a slightly more technical note, recovering from higher volume becomes harder as you age, so focusing on a smaller number (5ish) of reps at higher weight gives you adaptation without quite as much stress.
But I should be clear, when I said real lifting, I don't mean to exclude any form of well calibrated progressive overload, whether that's strength focused or hypertrophy focused. I do mean to exclude the "go to the gym and lift a 10 lb weight the same number of reps each time" BS