The biggest problem with some of the streamers (not all, and there are certainly “slower” ones) is that at this point in the game’s age, a lot of the streamers you see are speed-runners, who attempt to play the game as fast as possible regardless of score. While this play style absolutely has it’s charm and fans, it’s not what you’re looking for. What you want is something slower that you can watch and learn from. If you can, take a look at the OutsideXbox YouTube channel and search for some of their Hitman videos. While they play on Xbox, it’s not really any different than the PC in terms of gameplay so it’s readily transferrable to your system. Here’s a link to their Hitman playlist:
They’ve been doing Hitman videos since the initial release of Hitman in 2016 (and before but that may not be as relevant for you). They typically showcase three distinct playstyles in their “3 ways to play” videos - Mike is guns blazing, don’t care about stealth, don’t care about score. Jane is sort of middle of the road. Andy tries to always play silent assassin and get the highest score. Between the three, you should get a good sense of how you can improve your own play. None of the three are speed runners so they play a lot like you would probably do. Maybe watching something like that would help?