A new minor update to both iOS and Android Instagram apps will let you repost Instagram Stories you’ve been tagged in. If you have a public account, you will get a DM from the person that links to that Story post. You then get an option to share that post to your own Instagram Story. When you opt to share, you’ll be redirected to your Story editor page letting you do the usual editing you’d do for any other story you post. The name of the original poster is seen at the top, letting people tap on the account and view their profile.
Source: GSMArena