My fiance had a mortgage. In 2021 we refinanced and added me as a co-borrower. He pays all taxes interest and principal. Should I say I owned a house last year?

Yes, you are a co-owner of the house.  You did not indicate if you were married on or before 31 December 2021.  If you were married then you may file as married filing jointly and claim all of the deductible mortgage interest and taxes on your joint return.  However, if you were not married and each of you file as single only your fiance can deduct the mortgage and interest and taxes as he paid them in full and you did not pay any of them,

You have to itemize your deductions to be able to claim these items.  If your itemized deductions are less than the standard deduction TurboTax will automatically use the standard deduction.

To enter your property tax and any other itemized deductions follow these steps:

1. Sign in to your TurboTax account.
2. Enter itemized deductions in the search box.
3. In the results, box click on jump to itemized deductions.
4. Follow the screen prompts to enter your property tax and any other itemized deductions.