Not legally. Streaming apps allow offline downloads within their app (e.g., Prime Video), but they encrypt the file. You cannot transfer it as an MP4.
Occasionally, Warner Bros. content rotates onto Hotstar. Check the language selector; most extended editions include Tamil dubbing. The Hobbit The Battle Of The Five Armies Tamil Dubbed
Google Play Movies & TV offers the Tamil dubbed version for rent (approx ₹120-₹250). Streaming quality is excellent with no buffering issues. Not legally