If you've missed the deadline for filing your Income Tax Return (ITR) for AY 2020-21, you can still file it by applying for condonation of delay. However, the new portal currently only supports condonation for late ITR-V submissions. You may need to wait until this functionality is expanded or explore alternative methods if your reason for delay is genuine.
As the last date is already over, first you need to apply for condonation of delay. If the request is accepted by the proper officer, you will be able to file ITR for AY20-21.