How to find status of Refund for previous year tax return (2020)

I filed my last years tax return (not for 2021 but for 2020) with an extension in August of 2021.  I have not received the refund, How do I check on the status of a tax return fro 2020?  I have tried to use the IRS app IRS2Go but does not seem to check for 2020.