How big is the plant? A photo would help us tell whether it needs a different sized pot.

30 inches tall

Looks about the right size to me--so long as this is a plant that can colonize the bottom part of that super-deep pot.

But what about the roots growing out of the bottom of the pot, you ask--don't they need more room? Won't a small pot stunt the plant's growth? Shouldn't I plop it into a bigger pot and surround it with nice fresh soil? Well, because the roots are congested, the plant needs a full repotting, including removal of all the old soil, reduction of the root mass and a badly needed root pruning to get rid of thick roots and the ones that go in the wrong directions, and replanting it into (probably) the same sized pot with an aerated fast draining soil. After the roots have plenty of room to run and air to breath, your already lovely holly should really take off. For most plants, repotting should wait until the summer, but the timing is different if your holly goes dormant, so hopefully a tree person will pipe in.

I could be wrong about the pot size; maybe this plant grows at an insane rate that would let the roots colonize more of the pot, which would make oversteering less likely, or maybe you will use a very fast, highly aerated mix like Al's gritty mix that makes pot size almost irrelevant, but this is general advice that might get you going.

Good luck--I'd love to see pics of it in a year to see how it develops!

The photo is the shrub in the plastic pot from the nursery.

Should the new container be the same size or larger (how much larger?)

new pot could be the next size up, and then what is it, fathers day, get a serious repot when its next growth spurt starts … such a nice plant, can't you find a spot in the yard/

The "yard" is my condo development's common area (i.e., not my property)

I'd stay with the same size pot, but if the problem is the ugly nursery pot, you could get a nicer pot to put the current pot in. But if you really really want to do something now, potting up is a temporary solution.