One menu for every language
Most big films from other languages reach the streaming apps with several audio tracks. Start the film, tap the Audio and Subtitles icon, and pick Malayalam if it is there. The pan-India releases like RRR, Pushpa 2 - The Rule, K.G.F: Chapter 2, Kantara and Kalki 2898-AD usually carry it.
Malayalam films in other languages
It works the other way too. Manjummel Boys, Lokah Chapter 1: Chandra, L2: Empuraan and Marco travelled across India with Tamil, Telugu and Hindi tracks, which is how many non-Malayali friends first discover the industry.
Checking first
Each service chooses its own tracks, so check the audio list in the first minute. The Language line on each DVDPlay page shows the language the film was made in.
Subtitles
For the original sound with captions, see the subtitles guide.