The frame comes with 30mm in black metal spacers plus the carbon cone/spacer which sits over the head tube.
So question. Would you chance it fitting more spacers than that under the stem? I read on Google that 30mm is the max normally.
The taller, heavier, aggressive you are, the sketchier it becomes. If you use a lot of spacers, it's a good idea to use a longer / extra long expander plug. But on this bike it's a proprietary part.
Pretty sure you can use 45 or 50mm and you'll still be fine. Also, presumably, the more spacers you use, the less likely you are to be a watts monster and a daredevil in the 1st place.