Use Live Translation on iPhone – Apple Support

Use Live Translation with the Messages app On your iPhone, go to the Messages app, and tap the message that you want to translate. In the message, tap the person’s name at the top. Scroll down and tap to turn on Automatically Translate. Select languages for Translate From and Translate To. The first time you choose a language, tap to download the language. The languages might take a few …

https://support.apple.com/en-us/123720