[szszrk]

For me it's mostly about your awareness and motivation, and you can test both with almost every phone on the market (well at least on Android).

Just use the "ultra" power saving mode your current phone has. It's not a fully universal advise, but usually it will make your screen turn grayscale, disable background services, replace your launcher with a much simpler one and then allow you to add 3-5 apps to use. On my phones it's configurable (like, you can keep colors, etc).

You can still use 5G and read email, use an IM. But you have to prioritize and your notifications are severely limited.

I personally consolidated all mail to Thunderbird mobile which checks mail every 3-4 hours only and it had zero impact on me (I can always refresh manually if I need to confirm login email etc).