How to extrude a face in CadQuery

Use

face_to_extrude.wires().toPending().extrude(...)

Full example

import cadquery as cq

box = cq.Workplane("XY").box(1, 1, 1)

face_to_extrude = box.faces(">Z")

result = face_to_extrude.wires().toPending().extrude(2, taper=45)