Sending push notification at regular intervals

I have made an app, but I want to send a push notification to a user/all the users every 30 minutes.
Say they can be the users who haven’t opened the app for quite a time etc.

I can do the rest part, the main problem is how do I send a push notification every 30 minutes? I can’t think of the logic

Can someone pls help me

Try Automated Messages with Onesignal :

if you need more control … try to use Automation Service ( Make Platform For Example )

Use it & Onesignal API to send Notifications Under Certain Conditions & Times ( you can revive any data from your app with " Make Platform " via HTTP request … and use it to send Notifications through Onesignal API .

The solution seems really good, but can you please elaborate a bit on how can I actually do that?