For the same subject framing the dof is the same for the same aperture, simple as that. Take a head and shoulders with the 85 f1.2 at <f2 and you have less dof than the same framed portrait with the 200 f2 wide open. Obviously the perspective is very different. Take both shots at f2 and dof is the same.
Take a picture from the same place and crop to get the same framing and the 200 f2 has much shallower dof than the 85 f1.2 even wide open. You'd need an 85 f0.85 to get the same dof as the 200 at the same distance if you wanted/needed to crop the 85mm shot to the same framing. An 85 mm f 0.85 would have an aperture 100mm diameter, funnily enough a 200 f2 has a 100mm diameter aperture. If you use the Brenizer Technique
you can emulate an 85 f0.85 with the 200 or the 85 f1.2.
Using two different focal lengths from the same distance the size of the aperture is what determines dof, for the same framing (that is move closer with the shorter focal length) it is the f number.
If you take two images from the same place with two different focal lengths and then crop the shorter focal length to match the "compression"/perspective, is identical, the dof is not unless the apertures were the same physical size.