I'll assume that nobody has been in screen time, getting creative with permissions, and will assume that this device is not managed (no profiles) and no parental controls (again, screen time)... If those assumptions are incorrect, un-do the changes there, and try again...
Okay. First... Try a restart:
Restart your iPhone - Apple Support
Failing that... Back up, reset to factory, reload iOS, and restore the backup:
Restore your iPhone, iPad, or iPod to factory settings - Apple Support
Failing that, check with Apple Support. Use the Get Support link in the upper right. Discuss your options and alternatives.