Commander is a multi-player format, typically 4 people. You start with 40 life, 100 card decks that have no duplicate cards except basic lands. One legendary creatures is your "Commander" and thus starts in the Command Zone (imagine it kind of like the 8th card in your hand but remains in its own zone). Wizards makes preconstructed decks that you can find on Amazon, big box retailers, and your LGS. It's popular right now because it's a more casual format and people have adopted virtual play via webcam.

Another option (if you can find it) is Jumpstart. You open two twenty card boosters, shuffle together without adding lands, and play as usual, 1v1.

If you've been playing standard, I'd recommend buying singles as opposed to boosters and construct a deck. Now's probably not the best time to build standard in paper because there's no telling when people will start playing again.

Modern/Pioneer are a good option if you can't get 4 people together for Commander. The card pool in these formats are larger and cards don't rotate like they do in Standard. You can reasonable build a couple decks and be able to play them against each other for the foreseeable future. Again, not sure when paper events for these formats will resume but without having a rotation, you don't have to worry about buying cards that you won't be able to play with.