Bet sizing strategy also changes over time, there are trends which happen. Lately, the newest trend in bet-sizing seems to be the overbet - meaning you make a bet size that is like 1.5 times the current size of the pot. The idea is to balance
bluff overbets with value overbets so the opponent never knows which one it is. Personally, when someone overbets the pot, I'm clueless and have no idea how to play back against such an opponent except with the nuts (which is quite rare to hold the nuts when it happens)... apparently the use of solver software to study hand histories is where this trend has come from... thanks solvers. LOL
Another trend is the downward bet sizing in tournaments. Years ago it was standard to open the betting to 3x the big blind preflop, but over the years this sizing has gone down, first 2.5x became standard practice, and today in the modern game you'll quite often see 2.2x or even 2.1x being used.
However, if you're playing live cash games in a casino, you'll often see bet sizings of 4x the big blind or even higher, 5x being used. So it really depends on the format you're playing, and also the level you're at. High stakes tournaments mostly feature the 2.1x or 2.2x opens, but the micro tournaments filled with donks like me, I still open to 3x just because I'm old school and also because I don't play as many
hands as others do. The idea of a 2.2x sizing is that if you open a ton of hands, you want as small an opening size as possible because it can get expensive if you're opening often but with a bigger size.