Capture One offers a helpful tool to inspect photographs – Focus.
Focus tool always shows your primary variant image, and you can set up it the way you need it. Focus window is fully resizeable; you can make it huge and place it on a second display or make it small and put anywhere in the interface.
The best thing is that you can zoom in and out of your image in the Focus window separately from the main viewer:
Plus, Focus has a handy cursor tool Pick Focus Point to change displayed area quickly.