Hi. It’s great that you are doing research before getting a rabbit (or two).
Bunnies are very social animals and are often happier in pairs, although single buns who receive lots of people time can be happy too.
Do you have a rabbit rescue near you? If you’re not sure, check out the House Rabbit Society’s webpage (www.rabbit.org) for a list of rescues. If you do, you could adopt a bonded pair and that would save you a lot of work. Bonding can be difficult and time consuming. Most bunnies can eventually be bonded but there are rare cases where the bunnies are just too aggressive and bonding won’t work.
If you adopt two singles, they will need separate housing until they are fully bonded and neutral territory to do the bonding sessions.
You will need to make sure that both bunnies are spayed/neutered and given adequate hormone recovery time before attempting bonding. Age is not really a factor, although I would hesitate to bond an older senior with a very young bunny because the older bunny might find all that energy tiring. Size doesn’t matter much to bunnies either. I’ve seen lots and lots of very mismatched buns.