Content Search and Microsoft Teams

Please refer to the articles and information mentioned below,

1. Use Content Search in Microsoft Teams - Microsoft Teams | Microsoft Docs

Note: 
i. Content search provides a way to query Microsoft Teams information spanning Exchange, SharePoint Online, and OneDrive for Business.
ii. Teams doesn't support content search of a single channel, so the whole team must be searched.

2. Create and run a Content search in the Microsoft 365 compliance center - Microsoft 365 Compliance | Microsoft Docs

Note: You can search the mailbox associated with a Microsoft Team (for channel messages)

3. Content stored in Exchange Online mailboxes - Microsoft 365 Compliance | Microsoft Docs

Note: Conversations that are part of a Teams channel are associated with the Teams mailbox. Conversations that are part of the Chat list in Teams (also called 1 x N chats) are associated with the mailbox of the users who participate in the chat. Also, summary information for meetings and calls in a Teams channel are associated with mailboxes of users who dialed into the meeting or call. So when searching for Teams content, you would search the Teams mailbox for content in channel conversations and search user mailboxes for content in 1 x N chats.

4. Conduct an eDiscovery investigation of content - Microsoft Teams | Microsoft Docs

Note: Not all Teams content is eDiscoverable. This section of the article mentioned above shows the content types that you can search for using Microsoft eDiscovery tools

5. The general users can refer to Search for messages and more in Teams - Office Support (microsoft.com) as well