Use a comic book reader app
Rename the file extension from .cbr to .rar if needed
Open it with WinRAR, 7-Zip, or PeaZip
Extract the contents to view the images
Use Calibre with a comic reader plugin
Use CDisplayEx on Windows
Use YACReader on Windows, macOS, or Linux
Use ComicRack on Windows
Use Chunky on macOS
Use an online CBR viewer
Convert the CBR file to PDF or CBZ if needed