As someone that went from 5S to 2016 SE to 2020 SE which is my current phone, I've been very satisfied with the 2020 SE.
With each phone I have always taken steps to reduce battery usage, disabled background refresh, and manually turn on low power mode after charging every single time.
Not sure if you're doing it manually from the settings, but you can create a Shortcut that enables low power mode. I have a little icon that I press, but there might be an even better way (automatically trigger on unplug? IDK)
Is your hand large enough to handle the phone one-handed and touch anywhere on the screen with ease without risking a drop? If not, do you use some kind of magnet finger-ring case or similar case?
With each phone I have always taken steps to reduce battery usage, disabled background refresh, and manually turn on low power mode after charging every single time.