There are no support for higher order tetrahedrons, quadrilaterals or hexahedrons in dolfin.
However, in dolfinx, there is support up to 9th order triangles and quadrilaterals, 3rd order tetrahedrons and 2nd order hexahedrons.
See for instance Higher order mesh tests.
However, right now, we do not support higher order mesh functions, but its on the todo list.