https://www.merlinmotorsport.co.uk/p/bob-heath-anti-fog-visor-sprayanti-fog
Get some of that, any motorbike shop sells it.
I've used it forever on bike visors, ski goggles, desert goggles skydive goggles and airsoft goggles/glasses and never ever had any steaming up issues, it's the best working stuff on the market