Convection oven work very similar to air fryer. Infact Air fryer are smaller in size and loaded with accessories to rightly use the function. While convection oven get lost with lack of accessories to use the convection part along with complex functionalities made by worse by microwave cos. So all you need some simple air fryer/convection style accessories to make it possible.
Basically you need to understand that food items placed in convection as Air fryer need to get hot air from both upside and downside. So the racks or basket placed in convection oven need to have vent/ hole from bottom too for heat to enter. As convection oven/ air fryer uses fan to blow hot air from heating element to the food.
If you still know how to use convection part of your microwave oven (Read manual that came along or download manual pdf online from cos website) then all you need is these simple accessories that can help you achieve convection like results: