I had a new vanity installed in the bathroom. The old vanity was lower in height and not as deep.

What is the best option to extend the vent underneath the new bathroom so it reaches the edge of the vanity?

My goal is to make sure all the heat is not getting blown around in the vanity and getting out into the bathroom.

I want to the local Home Depot, it appears there are no ready to go pieces to fit, but there were sheets of material I could manipulate into a similar size to either tuck into or around the vent to extend it. Is that a reasonable thing to do or is there some other solution I should do?

See photo below to reference, it's the bottom of the vanity, where the vent comes out. (Ignore the temporary piece of cardboard covering the tile floor.) Thanks in advance!