This article explains how to find contacts on Instagram using the People Discover feature. The information applies to the Instagram app for iOS and Android, and to the Instagram website.
How to Find and Sync Contacts on Instagram
Here's how to sync your phone's contacts with the Instagram app so you can find and follow people you know:
Tap your profile icon.
Under Discover People, scroll through the list of recommended contacts and tap Follow under a profile or select See All.