It sounds like a lovebird if it has blue on the rump. There is a huge size difference between lovebirds and conures and they really don’t look that much alike other than having some of the same colors. There are many species of both, so I can’t randomly find a picture and assume it’s what you may have found. The best thing to do is search images. Lovebirds are not much larger than a parakeet, and mainly they have a heavier build than a parakeet. They have short, somewhat rounded tails. Conures range in size, but the species that would be green with some red are large – larger than a cockatiel – and all conures have long, pointed tails that are nearly as long as their body. They have a larger, more powerful beak than a lovebird. If the bird you found fits in your hand and has a short tail, then it is a species of lovebird. You can send me a photo at firstname.lastname@example.org and I can let you know what species of lovebird it is.
Since the bird was outside, you should take it to an avian vet to make sure it hasn’t picked up any diseases or parasites from wild birds. Parasites, especially, are a big concern because all wild birds have external and internal parasites. You can check 911ParrotAlert, https://www.911parrotalert.com/ for lovebirds that have been lost, because someone may be missing him a lot and may have posted a lost bird report. If he is tame, he may have come from somewhere near you, although many lost birds fly for miles before someone takes them in.
Thank you for asking Lafeber,