Android Question Where to download json file as Example

You need to register your own Firebase account.

The good thing is, it is free and you are given free credits by Google to use with your Firebase push notifications for 1 year.

No one can provide you with their json file. This has security concern and risk of being misused which can cause an amount charge to their credit card.

Possible someone may give you a json file but he/she may need to create a new project and delete it in the future from being misused.

If you want to learn, you should learn from start to end. You need to go through all the steps from registering an account and creating a project.

No point you get a json file if you missed out all the steps.

You need to start from tutorial of integrating firebase services