This is a good question. Not all gamblers check the legality of such transactions in advance. This is a good instinct)) I can reassure you that sports betting (or simply online casino games) is a normal practice in India. You do not need to be a citizen to participate in online betting on equal terms with locals. Here is an example of a good site -
https://ind1xbet.com/ The main thing you should remember is that you yourself are responsible for monitoring the accuracy of your tax reports.