Can You Put A Couch In Front Of A Heat Register

This is our new business firm, and I wanted to put the sofa along the back wall, facing the fireplace where I'one thousand hoping to add some built-ins and mount the Television set. Just, the big vent along the dorsum wall I believe is an air return vent, for our HVAC, and the realtor said we shouldn't cover it. Is that true? If so, What are my options? If absolutely necessary, I could put a long narrow sofa tabular array over the vent, to get the sofa at to the lowest degree partially off the wall to allow for circulation, (see photo example) but that is certainly not ideal. If the sofa is a few inches off the ground over the vent, would that allow enough flow?