There are only two kinds of permissions on a file, one is that you can view it and the other is that you can edit it. You could try the following step:
Step 1: Open Teams and select a file, and open in SharePoint.
Step 2: Manage access and edit whether this user is visible or edit.
Other than that, We found a relevant third-party app that might do what you want – encrypt files. Hope this link is helpful to you.
Note: Microsoft is providing this information as a convenience to you. The sites are not controlled by Microsoft. Microsoft cannot make any representations regarding the quality, safety, or suitability of any software or information found there. Please make sure that you completely understand the risk before retrieving any suggestions from the above link.
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