Corrugated plastic sheets are tough and flexible. You can easily bend them to a curved roof without losing material integrity. There is only one rule: stay within the allowed arch radius.
In simple terms, an arc is a segment of a circle, and its radius is equal to its circle's radius.
Your sheet's minimum bending radius is determined by its profile (corrugation) and thickness.
Typical DIY polycarbonate corrugated sheets can bend to an arc radius of 4,000mm. Some of the more robust sheets require a minimum radius of 7,000mm. Check the specs of your sheeting to be sure.