If you are trying to log in to your TurboTax account then the password is one that you created. You will be able to use the 'reset my password' tool and TurboTax will send you an email that will allow you to change it if you have forgotten it.
The pdf that you can download of your tax return is not password protected when it is generated by TurboTax. So if you are trying to view the return on a pdf that you have downloaded to your computer then that too is a password that you created. If you have forgotten that password then you can always log in to your TurboTax account and go to the 2023 return that you created there and print a new copy that will not be password protected.
@m-pm