Hi @sratim Samsung Devices generally heat up when charging,using apps for extended periods , having a lot of applications running in the background,downloading large files and using power intensive applications and syncing large amounts of data. Not usually too much of a concern though as you have an older Device which was released in 2015 it is possible the battery is under a bit of strain and you will not be receiving any updates. you can use an app such as CPU-z to find out the temperature, only real concern if above 43°C though.
Some imformation here https://www.samsung.com/uk/support/mobile-devices/is-there-something-wrong-with-my-samsung-mobile-de...
I do not work for Samsung or make Samsung Products but provide independent advice and valuable contributions.
