Has anyone tried to make 24" fenders fit a 26" bike by changing the fender braces ?
I found some 24" Columbia fenders that the OG paint matches my 26" frame .
You might get away with it on the front fender. It only has the fork crown to attach to. But the rear has the seatstay and chainstay areas to attach, those holes may not line up. The diameter difference is 2", but each radius is only an inch different, so the tires would probably clear if they are 1.75.
In my experience some fenders bend easily and allow quite enough of play to do it, and some others don't. It depends on material and profile. My estimation is that quite likely it won't work as well as you want to.
I was going to do a sex change on this 24” Higgins and I put all the stuff of a 26” boys frame. I used washers as spacers for mockup and it looked great.