iPhone randomly shuts off when not plugged to charge

like a week ago my phone randomly just shut off and I had to keep turning it back on then I charged it and then it turned back on and it wasn’t even dead and it turns off randomly every time my charger isn’t in my phone I don’t know what to do I might have a virus somehow idk please help mine is the only one in my house that does it I don’t understand why now I can’t even do anything with out my charger

[Re-Titled by Moderator]