There is no need to turn off your modern day smart phones and these devices are meant to operate 24/7, 365. Inside flagship smart phones, especially those with removable batteries, come with heat pipes and liquid cooling.

If your phone is running very hot and overheating, it only denotes that there are some rogue apps running in the background, of suffering from wake lock issues. Resolve the wake lock issue and the problem goes away almost immediately. You can't use apps to cool down the temperature of your phone.

I just restart phone omce a week to clear backgroud apps, or wake lock issue

That is not true. To pro long your phone lifespan and it's battery is about how you charge and optimize it. If you have a lemon battery, everything else would just run upside down and give you a bad experience.

yes. i set auto power off at 1.30 am. auto power on at 6.50 am but the phone wake up itself  following daily alarm at 6.00 am

built-in with android setting. well it depend of manufacture or android launcher
my old lenovo a850 4 years ago already have this setting.
it  call "scheduled power on/off'