The one UI is open to unlocked phones only.So if you got your phone through a carrier, then it's likely to have carrier software on it and not eligible for the Beta program.If it was bought through Samsung, argos or a shop similar, it should be fully...

And plus put the apps that you use very seldom on sleeping apps or deep sleeping apps.

Haan or phone charge kartay waqt bhi phone bohot zyada heat up hojata hai

You should get netflix or any other online streaming platform subscription.