When you download and open a new app, you’ll get a notification that asks if you want to let the app track your activity across other companies’ apps and websites. You’ll also see information about what the app would track. You can tap either Ask App not to Track or Allow.

You can also disable tracking across every app you download by going to Settings > Privacy > Tracking, and toggling off Allow Apps to Request to Track. This means any app that tries to ask for your permission will be automatically blocked from asking and informed that you have requested not to be tracked. You  can also disable tracking on app you have already downloaded.

For apps that you’ve already downloaded and may have tracking permissions set up for, you can still turn those permissions on or off on a per-app basis.
Under Settings, tap an app, and then tap to turn off Allow Tracking. Or go to Settings > Privacy > Tracking, and tap to turn on or off each app you’ll see in the list of apps that have requested permission to track your activity.