Can I push notify based on geo-fencing without an iOS App? I want to know, if there are any way to get notification when I entered in any marked geo area.

For instance when entering a mall, I want to push to devices a notification to download a specific app.

I know, it is possible with a third party app, that will read GPS coordinates, and then check is user location within specified region but I want to do this without creating app. 

Some where I heard it is possible with DSP (Demand Side Platform). 

Can any one suggest me regarding this, or how can I achieve my goal?
No. Apple includes find my phone and friends which lets the owner of the device set up geo fences with notification when those devices a device has permission to track cross a geofence. There is no hook to automate what you contemplate as the device just receives a notification. 

Similarly, the workflow automation let’s you get a location but not set up geofence push notifications. 

You need to make or use a third party app to use location notifications and APNS as you requested on iOS 12 and below. 

To achieve your goal without an app, convince Apple this needs to be added to the OS and to the workflow app to have geolocation triggers.