How vlc zoom - PortableApps VLC Media Player Portable

You can follow the guide to zoom videos in VLC media player.

Go to Tools > Preferences [CTRL + P].
Under Show settings (bottom-left), choose All.
Navigate to Video in Advanced Preferences.
Scroll down (on the right side) to the Zoom video option.
Set the zoom factor like 0.25, 0.5, 1, 2 and 5.
Click Save.

BTW, if the zoom feature is not workable in VLC, you can check this article for alternatives.

Source article: video players with zoom function.

In a common way, Interactive Zoom will appear in the upper left-hand corner of the media screen of VLC Media Player once it has been activated. It will be seen in the form of a small window that can enlarge the video content while moving your mouse to the part you would like to zoom in with VLC. You can check the link to see how to zoom in.

Under Adjustments and Effects window go to the Geometry tab, enable Magnification/Zoom option, to let it zoom in/out the video. You will see a small window at top left corner with main magnification control. Fill in the triangle by clicking it to zoom into the video. To view the desired video portion, move the square capturing screen across the box.