zone 6 is half the US.. and rather diverse.. give us a big city name...

and all you want to know about is a small line of boxwood???.. if not.. lets see the whole front of the house... a long term all inclusive plan .. would probably be better than trying to integrate many small area projects into a comprehensive landscape.. lets call it a 5 year plan ...

ken

Yes, you can keep box that height if it is regularly clipped. But it doesn't really have a yellow tint, unless it is under some stress. Or is a variegated cultivar. In the summer it should be deep green.

I am in NJ zone6, the picture is the front of the house & we just have a driveway to the left

I agree with ken about planning for the entire yard. It's important to repeat form and color across any facade to achieve a balance. The design can be asymetrical but not lopsided.

I think those boxwoods would be fine if you don’t mind keeping them trimmed. There are smaller boxwood varieties that would be closer to 21 inches, too, if you wanted to save yourself some work.

check out Ilex crenata 'Golden Soft Touch'

I'd look at dwarf conifers before I set myself up for monthly shearing year round on a blight susceptible boxwood. Browse Conifer Kingdom and see what dwarf, yellow cultivars they offer.

I would check out local nurseries what they have for your zone.