A Samsung phone us only over heating if you see a warning pop up message advising it is and in extreme circumstances it'll auto shut down.
Turning it iff will cool it down.
Check in your Battery and Device Care section to see if an app is using lasts of power and use the optimisation tool there too.
This may work > Clear Cache Files from the phone's System Partition Section > https://www.samsung.com/uk/support/mobile-devices/how-do-i-clear-the-cache-on-my-device/ You may need to insert your earphones or hook upto a powered On Laptop to access the Clear Partition Section. This may help with lag or stutters as this clears the phone of old/unused or broken cache files.There is also a Repair Apps option in the Menu System too.
If required a Samsung Experience Store or Samsung Service Centre can check out the phone.
I wish you all the best. 
