Can you run the phone from 100% to around 15% 🔋 and then go into your Device Care section and under battery tap on that and screenshot that also using the scroll capture option to capture all your apps , and also include the top status bar so we can see what's going on with your phone @lexis122
Some generic information is to.......
> Clear Cache Files from the phone's System Partition Section > https://www.samsung.com/uk/support/mobile-devices/how-do-i-clear-the-cache-on-my-device/ You may need to insert your earphones or hook upto a powered On Laptop to access the Clear Partition Section. This may help with lag or stutters as this clears the phone of old/unused or broken cache files.There is also a Repair Apps option in the Menu System too.
And.......
> Safe Mode > https://www.samsung.com/uk/support/mobile-devices/how-to-start-my-galaxy-device-in-safe-mode/ turns off downloaded apps and themes etc which may highlight an app or theme that's causing conflict.
Low network signal can affect battery.
I found Google Chrome was a resource hog so I now use Samsung Internet.
Scanning in Location uses lots of battery too.
Syncing in the background can use lots of battery 🔋 too.
You can run a diagnostic in your Samsung Members App and use the optimisation tool in your Device Care settings.
Unfortunately trying to pin point battery drain is a step by step slow process.
A Samsung Service Centre can check out the phone too.
I wish you all the best. 
