To get stronger, build a bit of lean muscle and improve bone health, 2 x 30min of challenging resistance training per week is enough for most people.
Is 3 x 30min or 2 x 45min better? Yep, if you can. But whether it’s worth the effort depends on the other being-an-adult stuff you’ve got sitting in your knee-deep soup bowl.
Reps and weight matter very little. As long as you take most sets to 1-3 reps from failure. I like 8-12 reps as a sweet spot for time efficiency.
Four sets per week per muscle group is a good number to aim for.