The native one in the device care setting is good enough on the S21U. Just click on the battery and it provides a full analysis.
If you want more data then you can install the battery optimiser on the good guardians app from Samsung store.
Good guardians is actually pretty decent at keeping the phone optimised.
Other than these two, you can use accubattery... but personally I prefer not to install any other Google play apps than are needed... and the device care / good guardians do a decent enough job.
Smiley
😀
- Smiley
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