cant create work profile when device owner exist

I have to say: I never tried but it doesn't make sense.

Why?:

BYOD (Bring Your Own Device) = A private device where nearly nothing is manageable regarding device settings but able to provide work apps etc. to a device owned by the employee. Finally: Work profile is already present and on such a device no one from the company has to manage/get access to the private part of the device (DO is the employee).

COPE (Company owned Personally enabled) = A nearly fully managed device but with a work profile on it, so private device with work part but with more access for the admin to setup device settings than on a BYOD device as this device is owned by the company. Finally: Work profile is already present on this type of device and on such a device no one from the company has to get access to the private part of the device (DO is the company but provides a private section for the employee).

COBO (Company Owned Business Only = fully managed): You have entire access to the device and it's settings and files. As you don't want as a private person someone get's access to the private part and this device is already entirely setup as a "work" device (with no private seperate section) there's no need for a work profile. (DO is the company and there's no private section)

So, in general it more looks like you are using wrong enrollment type as every possiblity is given here. I think you want to have a COPE device enrollment (factory reset before enrollment needed if your device was enrolled different before).