My dad got a Doogee S60 Lite which has an annoying Power Saving Mode app installed that turns agressive power saving on after a while, even though power saving is manually disabled within the app. This causes it to turn off the screen after 10 seconds of inactivity. To permanently remove the app, enable developer settings by pressing multiple times on the build number in the "about" settings menu and then enable ADB in the developer settings. Connect over USB and run the following command in the adb shell:
pm uninstall -k --user 0 com.wtk.psmmode
--user 0 argument means the default user, so it's not globally removed, but it appears to work for removing its annoying features.