@kaushiik I see no reason why you should wait for the 2020 return to be processed before filing the 2021 tax return.
However, if you are going to use TurboTax, you cannot e-file the 2021 tax return, it can only be printed and mailed. There may be other professional services who can e-file the 2021 return but that is going to cost you.
To complete and file a 2021 tax return using TurboTax you would need to purchase, download and install on a personal computer one of the 2021 desktop editions from this website - https://turbotax.intuit.com/personal-taxes/past-years-products/
