My phone won’t update to iOS 13

See: Get help with over-the-air iOS updates - Apple Support

Update your iPhone, iPad, or iPod touch - Apple Support

Please check: Settings - iPhone Storage. If you see an iOS update file here, delete it and check again. The correct update will be 13.2.3

If you have used a beta version of iOS on the phone, remove the beta profile.

ClumsyGeek wrote:

I have enough space and no updates or beta...It’s requesting to download iOS 13.1.2

Correct, which sometimes indicates that an update file has been previously downloaded but not installed. You will not be able to install that version, as it is no longer current.