If I never file my taxes and I didn't get my 2020 stimulus or my 2021 stimulus how do I get it now and how long do I have to get it

I know for 2021 you can do a free return and skip the income portion and claim your stimulus there but is today the last day for that and for 2020 some say you have to file a return just like 2021 and then some say there is a rebate recovery form you fill out. I am so confused and how long do you have for that too