Currently I'm on 32s Michelin PowerCups. I'd say 36 won't fit but 34-35 might.
It all depends on your rim/tyre combination and the resulting actual measured dimensions, i did a experiment mounting panaracer gravelking slick 38 on i29 rims -> WAM 43mm. Very little margins for mud/debree around the chainstays (~2mm) and the front deraileur were (just) touching the tyre.
I'm now running Vittoria N.EXT 34mm on i23 rims, WAM36 this leaves 6mm clearance to the chainstays.
Based on this i'd say if you are modest with the internal width (<=23-24mm) a 38mm tyre will problably be OK but if you want to be on the safe side go for 34-36mm tyres.