Hi
In event moduel have a setting that gives all riders the same weight, height, age and bike.
Just the riders effort counts.
Could be interesting results in that kind of race 
This would handicap a lot of rides.
Another more interesting option is FTP handicapping. Use the same CdA, Crr, and weight for riders but adjust their power output as w/kg based upon their FTP calculated using their best performance on Zwift.
If someone with a 175 FTP races someone with a 325 FTP for one hour and they both put out exactly their FTP, and don’t draft at all, they finish at the same time. So the results are based on your best effort and not necessarily your ability. Add drafting and elevation dynamics and it makes for a more interesting race based on how hard you work and not how fit you are.
This also allows for “flyers” to race because if their settings allow them to have a 1000 watt FTP on Zwift they will still be equalized to everyone else.
There already is a calculator that asks for your FTP and automatically gives you a height/weight handicap to have everyone riding at the same “level” - so a Cat D rider in Z5 will be equally matched to a Cat A rider in Z5.
At the moment, I run handicap races based on previous race times around the course, giving staggered start times so that everyone should be close together towards the finish line. I’m also looking at running races based on weight & height handicaps along the lines you suggested.