You can "zoom" into video when viewing camera footage in the video player.
To zoom into video:
Hover over the video with your cursor and use the scroll wheel on your mouse to zoom in and out.
OR
Hover over the video > select the magnifying glass icon > use the slider to zoom:
Tip: When viewing multiple cameras at once, you can hover over each camera individually and use either method (mouse wheel scroll or magnifying glass icon) to zoom into the respective camera.