You can now link your devices and apps with your Microsoft account using the link code without requiring you to enter your account details manually.

You can quickly link your Microsoft account with devices with a code, and apps or services that prompt you to use Microsoft Account Sign-In. Here's how.

Follow this link to Minecraft Java’s profile manager Log in using the Microsoft account associated with the Minecraft log-in Select “Profile Name” Change to the desired name and save ...

This Fall, new Minecraft Java players will need to create a Microsoft account to log-in. Meanwhile, existing Mojang accounts will need to migrate in early 2021.