Question about lifting

I'm a teenager and I started going to the gym around 2 months ago.

I did boxing and calisthenics before so I already had strenght and didn't actually start from 0.

Ever since I've been to the gym I've notices progress, but my question is, should I go to failure every single set I do or is that bad? Also, is it true that less weight+more reps= muscle and more weight+less reps =strenght?

Ty, God bless