Will this ductwork for my range hood work?
One way to resolve this is to transition from 6” to 5” duct in ceiling space. Dropping below ceiling with 5” duct will give you another 1/2” clearance from the wall.
The reduced size duct on a short run from blower to ceiling probably has a minor impact on airflow. 6” duct is rated for  up to 600 cfm. If your blower is pushing 400-500  there is no significant impact to airflow.  If it is pushing 600 or more there will be a bit  of extra noise.  If it is well over 600cfm your duct is too small .