Well, this was disappointing to find...I really would've thought it was possible in Designer by now.
I've been using this tool since Illustrator '88...and that came out in 1987. Between morphing/blending shapes and colors, it's a HUGE time-saver. Auto-trace has been around just as long but I think I'd even choose blend over trace if Serif isn't interested in both. I know all the Affinity programs have been written from zero, but Serif was there back in the day when these features were in use...