UTMs (Urchin Tracking Modules) are a great way to track the performance of your push notification campaigns, and the behavior of the users who get to your app through a push notification, in Google Analytics.
The first step would be to create a URL that contains all the UTM parameters for your campaign, you can do this easily with this tool: https://ga-dev-tools.google/campaign-url-builder/
Here is an example of how your URL will look like after you add your UTM parameters: https://mobiloud.com/?utm_source=help_article&utm_medium=link&utm_campaign=utm_education
Make sure your have Google Analytics configured to track your app usage, you can check this guide for more details: https://www.mobiloud.com/docs/track-app-data-in-google-analytics-with-google-tag-manager-gtm
Now let's head to OneSignal to send a push notification: https://onesignal.com
In your account's "Push" area, on the top right side, click "New push":
Fill your push notification content with a title, message, and image (optional):
For your notification URL scroll a bit further until you see the "Additional Data" field. In the first field type "url", and in the second one add your URL containing the UTM parameters:
That's it! You can now send the notification to your users and track the UTM parameters via your Google Analytics account.