The fact is the states decide how they vote. We've had mail-in for 10 years. I get my ballot in the mail and I mail it back. What could be simpler? No, we've never had any fraud so put that down as a fact that mail-in is secure. The clincher is you can't get there in 4 months so no need to even try. It takes years to perfect that system. No state should be considering changing their systems because of Covid, too late in the game. Feds don't have any business telling states how they should vote. Now, if congress wants to give the USPS 20 billion dollars so they can better move the ballots that's different because a lot more people will be voting by mail this year. I don't have a problem with that.
Both Trump and the dems are using this as an election issue. Not a real good idea for anyone but Trump made it an issue that the dem congress felt a need to respond to. You would more or less expect that they would just because they just aren't going to give him a pass on his totally false narrative and the actions of his newly appointed boot licker.
So yeah, no new legislation is required unless it's to pump some money into the USPS so they can continue to do their job. They sounded the crash alarm months before it became apparent that lots more people will be voting by mail because of covid.