It is possible to create Admin accounts on DEP enrolled Mac devices.
To add an Admin account, enable the Configure user accounts option in the DEP policy that is applied to the device during the enrollment. On enabling the option, you can configure several other options such as the name of the administrator and home folder, the password for the account, whether to hide the account, etc..
After creating the policy, associate the same to the device during enrollment for the addition of the admin user.
Kindly use the help link for info on adding Admin accounts to macOS devices.