I go into device maintenance and put all the apps that I use frequently into deep sleep mode so once the app is closed it won't run in the background . I started doing this on the s9 plus also on the S10 plus. so far it's working on my note 20 ultra
I know most people are in love with the 120hz option. Personally I prefer higher res so I switched to WQHD+, definitely gives slightly better battery life. It is nothing to write home about but still noticible.
The battery life on the note 20 ultra is extremely disappointing. I have never had regrets about buying a Samsung phone but I actually do this time around. I don't mind the headphones not being included in the box but when the phone dies fast and charges slow its a real issue. I don't do anything that I didn't do on my note 10+ or my s20 ultra but yet this battery drains at a much faster rate. This is not acceptable for a $1300 phone