How do I sync my iPhone 13 to my iPad?

Through iCloud.

Change which apps sync and store data with iCloud - Apple Support

You don't easily, although you could do some things using iCloud.

I suppose you could manually back up your iPhone to your Mac and then restore the iPad with the iPhone backup on the Mac, but that's a lot of work and you'll spend a ton of time trying to keep the iPhone and and iPad looking the same.

Hello there, Ousee12!

I have some advice for you, you can sync your iPhone 13 to your iPad by using iCloud.

I hope this helps you, have a nice day, cheers! ^_^