If you want to exploit network speeds, use a network cable. USB is not a network cable.
USB is designed to transfer data between hard drives over a short distance. Meaning, a USB cable has a very low tolerance to distance. I'm not confident...perhaps someone can check me...but USB-C may be 10 to 15 feet.
Even if you directly connect a Cat-5e cable to your DOCSIS, you still won't get 1 Gbps. Routing overhead and data retransmission consume about 10 percent of your bandwidth. Although Cox guarantees up to 1 Gbps, they're including the necessary overhead and retransmissions..."badput"...into your throughput.
You also share the network outside your house with your neighbors so if one is hosting a 4K game server, it'll affect the available bandwidth to your house.
If you're getting 700 Mbps through a USB adapter, you're doing pretty GD good. 450 Mbps wireless sounds about right.