This is according to Apple’s updated developer guidelines where according to the wording, “Apps may enable gifting of items that are eligible for in-app purchase to others. Such gifts may only be refunded to the original purchaser and may not be exchanged.” As pointed out by AppleInsider, previously the ability to gift in-app purchases were explicitly banned, which is why some apps such as LINE have removed the ability to send stickers as gifts directly within the app itself (you can send it as a gift via LINE’s website).
That being said, it is unclear as to which apps will be taking advantage of this feature as there doesn’t seem to be any apps that have offered the feature just yet, so it is possible that Apple could still be working on the feature and that it might not necessarily be available just yet, but presumably it should be arriving soon given the change to the developer guidelines. Either way we’ll just have to wait and see, but don’t be surprised if you start seeing the ability to gift certain in-app purchases to your friends and family.