You can always upgrade to a higher-level product in TurboTax Online. Just use the Upgrade button that will appear on the bottom of the left side menu after you finish the “My Info” part of the return. If you want to downgrade, you will need to start a new return in the product that you want to use.
Please note that for 2021, you will need to upgrade your return if you are using a TurboTax product that doesn’t include what you need for your specific tax situation. Please see these TurboTax FAQs for more information: