If you’re trying to get as much battery life out of your Samsung Galaxy S20 as possible, then you might want to consider disabling the 120Hz display on the phone. This is because according a very comprehensive review of the phone by AnandTech, they have found that the 120Hz display is very taxing on the phone’s battery.
For example, in terms of web browsing, the Samsung Galaxy S20 Ultra managed to achieve 14.05 hours using a 60Hz display, but when the display is cranked to 120Hz, the phone only managed 11.33 hours, nearly 3 hours less battery life compared to when it was using a 60Hz display.
Also, it should be noted that this is based off the Galaxy S20 Ultra variant that uses the Snapdragon 865 chipset. It appears that the Exynos version is less efficient, where it managed 12.28 hours with a 60Hz display, and 10.18 hours with a 120Hz display, but either way this suggests that both variants will benefit from you lowering the refresh rate on the phone.
This review of the phone’s battery life is one of the reasons why many companies have been somewhat hesitant to include a 120Hz display in their phones. If you’re not too fussed about having a buttery smooth display, then bringing the refresh rate back down to 60Hz should squeeze a few extra hours out of the phone.