Hi,I do not know how to use MRtrix3 to view these .stats files.
These look to me like FreeSurfer Stats files? There is no facility within MRtrix3 to view these files, but more to the point, they should just be regular text files, which you should be able to open in any regular text editor. On Windows, you could use Wordpad for that (though it’s not ideal as a pure text editor, if you need to do a lot of text editing, you can find plenty of alternatives online)