We can talk about Android's all-day battery life, but the quickest way to make an instant difference in your phone's longevity is to adjust your screen settings.
First, lower your screen brightness (either in the quick settings panel that appears when you swipe down twice from the top of the screen, or in the display section of your system settings). The screen consumes more power than anything else on your device, and the less you can comfortably use it, the longer your phone will live with each charge. If your phone is running Android 9 or later, you can also look for the Adaptive Brightness option which will automatically adjust the brightness level based on your current environment.
Second, set the "Screen timeout" setting (also in the Display section of system settings) to the lowest value you can tolerate. The less time your screen stays on when not in use, the less unnecessary battery power your phone will burn.
And third, if you have Android 10 or higher, look in the same area of your system settings for the Dark Theme option. Dark colors tend to consume less power than the bright colors that are on most interfaces by default, so switching to the Dark Theme either all the time or even on a timeline from sunset to sunrise should extend your phone battery a bit.
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