When you attach window crown molding to the board installed at the top of the window. What other molding goes at the sides and bottom? If any.

Usually a plain or detailed side trim that is about 1/8 inch recessed under the crown, and slightly narrower than the crown is high.
Under the sill cap, an apron that is plain, often narrower than either trim above, and often curved down, or routed and angled downward at each end.
It's mostly what you like, except for the crown being the thickest to protect endgrain of what is below from rain.

Thank you