I have received a message considering of Hindi transcript which I want to translate through the messaging app but says it doesn’t support Hindi?

Re: messaging app ... says it doesn’t support Hindi?

You might want to use something like the free, instant, Google translate service for this one message. (ie: Copy and paste text into a web browser) (No need to log-in)

or

For the iPhone itself: how to: Change the language and region

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Re: "would request better intellectual people to consider this things on iOS devices"

You might want to send feedback / request / to those who work at Apple:

Web-form : Feedback - Messages for iOS and iPadOS - Apple

Apple publishes the current language coverage of its translation services at

iOS and iPadOS - Feature Availability - Apple

There is also the word-by-word dictionary service, which you access via Look Up (instead of Translate), which does include Hindi and could be useful for short texts

iOS and iPadOS - Feature Availability - Apple