Currently, it is lacking of the support for multiple accounts. This feature is in working and you could vote for and pay attention to this link.
The best method for maintaining multiple Microsoft Teams accounts seamlessly is using the web app(https://teams.microsoft.com) for Teams with multiple browser profiles. It’ll allow you to have separate login sessions within each profile.
Teams mobile app for both iOS and Android supports signing in with multiple accounts. You could refer to the following image:
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