Overheating

It is not clear here in your post about the ambient temperature in your area where you are using the iPhone. However --> Keeping iPhone, iPad, and iPod touch within acceptable ...

Store the device where the temperature is between -20º and 45º C (-4º to 113º F). Don’t leave the device in your car, because temperatures in parked cars can exceed this range.

Use iOS devices where the ambient temperature is between 0º and 35º C (32º to 95º F). Low- or high-temperature conditions might cause the device to change its behaviour to regulate its temperature. Using an iOS device in very cold conditions outside of its operating range might temporarily shorten battery life and could cause the device to turn off. Battery life will return to normal when you bring the device back to higher ambient temperatures. Using an iOS device in very hot conditions can permanently shorten battery life.

Take a Backup either on iCloud after enabling all iCloud Options ((Preferable) or iTunes (Encrypted).

Settings > General > Reset > Erase All Content & Settings > [Do not keep anything on the device]

If you are given the option to Erase and Erase and Keep Data Plan (Dual SIM) Then Select Erase and Keep Data Plan

Set it up as a new device and check if the same issue recurs, probably it won't.

• If it does then you need to take your device for repair or service
• If it doesn't, then there is no issue with the device. Restoring from the backup may bring the issue back.
• Set it up as a new device and use iCloud and bring back synced data in iCloud, like Contacts, Calendars, Bookmarks, Mail, Notes, Voice Memos, Messages*, shared photos, iCloud Photos*, Health data, call history, and files you store in iCloud Drive.
• Download all Apps from the App Store one by one especially those which did not have any App Data stored on your device

Use genuine cable --> Identify counterfeit or uncertified Lightning connector accessories ...