If I just sent in a paper return for a friend that didn't know anything about getting his rebate recovery from 2020 will they still send the $1800

No. It's too late to get a refund for 2020.

If you are eligible, you have only a few days remaining to file for the 2021 rebate.

It is too late for the recovery rebate credit for 2020.   If they did not receive the 3rd EIP payment which was issued for 2021, a 2021 return must be filed no later than April 15, 2025 or it will be too late for that one.