First tip, always keep dark mode on if that's ok with you. Secondly, go to settings, then go to connections, go to more connection settings and turn off nearby device scanning as that setting uses a lot of battery in the background. The third tip is to uninstall any apps that you don't use because the less apps there are, the less that your battery will be wasted in the background. Before I changed all these settings on my s20 plus, the battery would last about 6.5 hours but now I have changed the settings, the battery gives me about 10 to 12 hours before it runs out of battery which is a huge improvement. Please use these tips and you will have a much longer lasting phone and battery. Hope this helped!
