@Louis-Philippe Perras Yes, it is possible to link multiple identity providers to a user profile with Microsoft Entra External ID <sup>12</sup>. This allows users to log in using different providers such as Microsoft, Google, Facebook, or local accounts, but still be the same user <sup>12</sup>.
To achieve this, you can create a sign-up and sign-in user flow that allows users to sign in using multiple identity providers <sup>3</sup>. You can configure the user flow to include the desired identity providers and then link the user’s external identities to their profile <sup>3</sup>. This will allow the user to log in using any of the linked identity providers and still be the same user <sup>3</sup>.
You can also use the Azure AD B2C custom policies to link multiple identity providers to a user profile <sup>1</sup>. This allows you to create a custom policy that includes the desired identity providers and then link the user’s external identities to their profile <sup>1</sup>. This will allow the user to log in using any of the linked identity providers and still be the same user <sup>1</sup>.
I hope this helps! Let me know if you have any other questions.