Still persisting with Opus as it appears to be the best alternative file manager! I have Powertoys installed and can see previews of svg files using Opus's file viewer, but the zoom controls (Zoom in, Zoom out, Ft to page, Fit width) do not work. I appreciate you rely on third party viewers like Powertoys, but you did say to ask if I wanted more help with this. If nothing can be done, that's fine - just checking.
AFAIK there isn't a way to zoom in and out with preview handlers, so we have no way to hook the buttons up to send a request to that type of viewer.
(If the same viewer has a way to zoom in and out in File Explorer's viewer pane which doesn't work in Opus then we can look into that, but AFAIK it isn't part of the preview handler spec.)
The buttons are there for other types of viewers (e.g. Opus's internal image viewer, and some of the native Opus viewer plugins written for our own API rather than Microsoft's preview handler API) where zooming is possible.