Instagram users who have access to the multiple accounts feature will see the option to add additional accounts in the Settings menu through a new "Add Account" heading. Once a second or third account is added, switching between them can be done with just a couple of taps. With multiple accounts logged in, notifications for Likes and Comments will also have a header to let you know which account is receiving the alert.
Multi-user support has been a highly desired feature on Instagram for several years. The first hint of support came in late 2015, when Instagram began testing the feature on Android. It is not clear when multiple account support will see a wider release for iOS users as Instagram has not yet made an official announcement.