Looks like a Comet Goldfish to me, I think they can reach lengths of 12 inches. They will need room to roam!
These fish are very active and will spend their days swimming around their habitat. If it’s not big enough for them to do this, you will encounter problems at some point. 50 gallons is the recommended aquarium size for these fish, ideally they are more suited to a pond.
Welcome to the forum and to your fishkeeping journey!
Those are common goldfish. Pretty demanding fish, they will need a very big (nothing under 75 gallons for both, in my opinion) tank or pond eventually, because they can grow to a foot long. While they're under ~5 inches they will do fine in a 20 gallon, but bigger is always better. They are very messy so you'll need a high powered filter and thorough understanding of the nitrogen cycle (click the link for more info). A heater isn't necessary unless the tank temperature will drop to near freezing, thankfully. Feed them a high quality goldfish pellet, plus blanched veggies chopped into bite sizes roughly three times a week. Especially use shelled peas, this prevents any constipation or swim bladder issues.
It's a lot of info, but best to know as soon as possible so you can provide for them as best you can. It's a shame they give any fish away at carnivals, especially goldfish, without informing people of their proper care.