Don't be conscious about heating of a device it is quite normal especially if it a year/s old, Exynos variants, and also if you usually use mobile data, or fast charging or having so many background apps. Don't worry it will not explode like the note 7 fiasco before.
Here's some tips for you!
For the battery if you want longer battery life and not to automatically run the background apps, you can check at settings > device care > battery > app power management > deep sleeping apps or sleeping apps. put your very rarely use app to deep sleep and your rarely use app to sleep. don't put any apps on "apps that won't be put to sleep" let the system automatically add the important apps to it. 😉
