Your link for wifi calling doesn't work. It has a period at the end. See the link in my post for comparison. I only mention it for trending reasons because it seems to be a typo made by only moderators, different moderators, both recently and in the past.
Also, is there anyway to find out when that page was last updated? For example, I don't see Pixel phones mentioned, but I have heard from customers that it did work after a recent android update. I guess it doesn't matter yet since we don't know OP's phone or OS version, but I predict it will be relevant. Last, I see we agree that main thing OP should do is move around to get signal. To that end, I also suggest OP make sure airplane mode is not on, and that the SIM is inserted correctly. Not even sure Cox uses SIM vs eSIM, but if they gave one, make sure it's inserted.