In DesignModeler, create planes about 0.5 m away from the edge of the connection area along each of the four beams coming into the cross intersection. Use those planes to slice through the beam.

In Mechanical, create a Bonded Contact contact to reconnect the four cut off pieces. Now you can mesh the center bodies with a refined mesh and the outer arms with a coarse mesh.

To further reduce the mesh size, you can replace the outer arms with Beam elements.