It’s not necessary to make indexing of apps on Google Search to have the app on Play Store. As far as I understand your question.

But as @Jax has written maybe you need to add your privacy policy if you hold some user data on the web, but I don’t know a thing about the law.
My idea is that you can simply add some privacy policy as .md file in Github public repository.

I’m creating a TicTacToe application in which a user can play against a computer, another player, another player through wifi/internet. My application doesn’t have any links or connections to other application Is indexing my application on google search is necessary, if yes how can I do that if I don’t have any website.