Select the puppet in the Project panel, then make sure "Render as Vector" is checked in the Properties panel.
I tried that, and I think that only works within Character Animator. Once I import a puppet's chproj into After Effects, and I zoom into the puppet 200%, it's still blurs like a bitmap.
Ah, yeah, content via Dynamic Link (either from Character, Premiere Pro, etc.) is pixels only at this time. I've added your request to the existing one for this capability.
For now, you would need to scale it using the Transform behavior in Character. (If you have CH and AE open at the same time, and you just dragged the CH scene from its Project panel into AE's Project panel, you can flip back to CH to adjust the Transform > Scale values, then switch back to AE to see if OK.)