1. Don't use your phone while charging
2. Charge it in a less hot place.
3. If you have put a cover on your phone then take it out while charging.
Normal usage isn’t a proper condition. "Normal usage" term varies person to person. Can you elaborate which apps are causing this heating issue?
Dear Samsung Member,
Greetings from Samsung Customer Support!
Please visit this mentioned link to resolve your device heating issue: https://www.samsung.com/in/support/mobile-devices/why-the-device-heats-up-during-use/
For further assistance, register your concern in Samsung Members Application (Open Samsung Members Application > Get help > Send Feedback > Error report/Ask questions).
Thank you for writing to Samsung.
Samsung Customer Support