PCB Layout and Trace Widths for Buck Converter
You should turn these traces into large copper pours.

You need to co-locate the capacitor with the output of the inductor. That will reduce noise in your circuit, since there is a large AC current flowing out of the inductor into the capacitor at all times.

Consider that the AC path into the capacitor needs to make its circuit back to the ground of the IC, and move it around accordingly.

Make your switching node as small as possible to eliminate noise.C3 looks pretty good, but after that it gets pretty tangled.

You need to add vias under the ground pad of the IC for heat conduction into the ground plane.