It wholly depends on the type of shapewear you are talking about here.
If it’s a waist shaper, it extends till the hip and yes, you have all the room to wear panties.
If it’s going to be a thigh shaper; then, this will extend to mid-thigh. In this case, there are two options. You can either wear panties or not depending on what one is comfortable in. But, in most situations, it is recommended that you wear an undergarment for hygienic reasons.