According to this page Can I claim prior year medical expenses? of TurboTax, "Yes, you can claim any eligible medical expenses if they occurred in a 12-month period that ends in the current tax year. After you enter your medical expenses, TurboTax will prompt you to choose your 12-month claim period. For example, the oldest medical expense that you can claim on your 2021 return is an expense from January 2, 2020, using a claim period of January 2, 2020, to January 1, 2021".
For more information on medical expenses of prior years visit this page of the Canada Revenue Agency: - Medical Expenses 2021
Here is the FAQ on how to enter medical expenses in TurboTax Online: - How do I enter my medical expenses?
Thank you for choosing TurboTax.