As reported by Android Police, Instagram is slowly rolling out multiple accounts feature on Android devices. This could really be a helpful feature for people who manage multiple accounts, such as personal or work accounts.
Though the feature is not yet available on iOS, but it is live on Android version 7.12.0 of the app.
If you have the said version of the app, go to Settings, then scroll to the bottom, even below About section. There you should see Add Account option, tap it and you’ll be able to add another account or create a new one from scratch.
When added, you should see the option to switch to another account under your Instagram nick name. Additionally, you can log out of your accounts individually or all accounts altogether.
Try updating the app as the feature is already rolling out to users, as reported.