People already build relationships through apps that wouldn't have otherwise happened (be it discord or tinder), though neither is really very good at that.
If you want to build relationships with people who live near you the app should have some element of seeing content from people nearby you (presumably within your age bracket too). And also more interactivity from viewers (you can see a moderate amount of interactivity even in youtube communities).
Discord totally does encourage creating social connections. It has the idea of "friends", and does things like show you what games people are playing to enable people to join in games together or at the very least chat about it.
If you want to build relationships with people who live near you the app should have some element of seeing content from people nearby you (presumably within your age bracket too). And also more interactivity from viewers (you can see a moderate amount of interactivity even in youtube communities).