Tile overlapping existing toilet flange - flange extenders don't fit
This is honestly a 30 second job with an angle grinder (plus diamond wheel).   Wet area (rewet wheel and area if this takes any significant time), make sure grinder is pretty close to 90 degrees, if worried about hitting something under then just go halfway and chip out.   Your cuts don't have to be great as they will be covered by toilet.   Would also suggest taping the area you are cutting.