Hey there Dechris_mode,
Thanks for reaching out to Apple Support Communities. I understand you’d like to know if Keynote supports zooming using a mouse or trackpad. I’ll be happy to help with this.
According to Apple, ‘To quickly zoom in or out, choose View > Zoom > Zoom In to enlarge a slide or View > Zoom > Zoom Out to reduce it. You can choose these commands multiple times to reduce a slide to 10 percent or enlarge it to 400 percent.’ You can read more about using the zoom feature in Keynote here:
Expand and zoom your workspace in Keynote on Mac
There’s a Zoom feature built in to your macOS. Take a look at this article for more detail:
Use your mouse to zoom in to make an image larger on Mac
Regards.