Currently the 2021 cap, percent of NFL revenues as dictated by the CBA, is unknown. The speculation is that revenue is down year over year and that will cause a decrease in the salary cap. Around 180 million is the number I have been seeing recently but we will definitely know by the start of the new league year March 17th. For reference, the cap for 2020 was 198 million.
The Rams are over the cap. For the new league year teams need to have their top 51 contracts total at or under the cap. The Rams are around 210 mil including dead money. The Stafford deal cost around 7 mil in cap space.
The Rams have over five mil in 2020 cap space they can carry over to 2021 . But the key will be contract restructures--giving players cash from salary now and amortizing those amounts over the remaining years of their contracts. So cap cheaper now while increasing each future year's cap charge.
Stafford, Donald, Kupp, Woods, Ramsey are likely targets.
Basically, the Rams have no money. They can create money for a future cost and will have to do so. I don't expect them to sign any free agents over a few mil per. They also avoid signing free agents for comp pick purposes.
Hope that helps.