Hello guys is it possible to have 2 transcribers to have an agent that can speak both french and english depending on the language the caller uses ?

Yes, you can create an agent that speaks both French and English by using a multilingual transcriber like Deepgram, a bilingual voice provider like Azure or Eleven Labs, and enabling automatic language detection to switch languages based on the caller.

Is there a step by step how to enable language detection please, also i ve seen that deepgram multi only works for spanish and english

Kindly follow the guide https://docs.vapi.ai/customization/multilingual