I used to face the same issues at the beginning, so I'm gonna tell you what I did and when I saw real benefits.
I noticed that when I charge my phone while being turned off, battery lasts less. Also it lasts less if I charge it in slow charge, also it heats up a lot.
So my advice is charge your phone while being on, with fast charge, up to 100%
Avoid every battery saving option (they'll drain your battery more, this phone is made to be stressed out ahahah), 144hz refresh, and do whatever you want. No need to close background apps continuously. I stopped doing it and it works fine. My battery lasts from one full day (whenever I use it a lot) to 1 day and a half, or even two days if I'm busy and I don't use it very much.