We recently installed a new toilet after we remodeled the bathroom. The new flooring is approximately 1/2' lower than the original floor, thus leaving the toilet bowl flange sticking up.
Are there "spacers" in the form of a porcelain plate to match the toilet that will allow the toilet bowl to be directly mounted to the flange without overhang?
My plumber has given me an estimate to cut the flange to match the floor which I prefer not to do.

"Are there "spacers" in the form of a porcelain plate to match the toilet that will allow the toilet bowl to be directly mounted to the flange without overhang?"
No! Shims have to be soft like sheet lead or plastic so they won't fracture and crack the brittle china of the bowl.
I guess you could use flange extenders to extend the flange and shim the bowl but the space would have to be filled and caulked with white Dap Tub and Tile Caulk. This would give the toilet a odd look but it's doable. I would cut the flange back to floor level and install a inside flange,(see image) if it were me. Good luck, Tom