I have ethernet ports in every room in the newly built house.

So, from the main router in the house there should be a wired ethernet cable to port covered on the left. ( I think the port on right is coaxial )

You can attach additional powered ethernet switches to these ports to add more ports.

Kinda but no.

Phone cable is thinner because it has only 4 smaller wires running inside it (and has smaller connections) while Ethernet has 8 and has bigger connections

As others have said, most new build Morden homes should be wired like this.

All these points should return to a central location, most likely in your plant room or attic.

You do not need to wire them up to your router unless you want to.

Your domestic router will have 4 free ports on the back that you could connect 4 of those cables to, how you figure that out yourself is a bit hint and miss if the cables and ports aren't label.

If you need/want to wire up even more ports you would need to get a switch they aren't expensive

Wired connections are better the wireless, so your typical uses for these would be if you plan to work from home from a particular room, if possible wire in your connection.

If you have a particularly weak wireless signal in a part of the home you can get a wired extender and connect it, or you could use the ports to wire in a mesh system like the TP link deco etc

Most likely they will have to add the patch panel themselves, can't imagine the builders leaving any more than a bunch of loose cables sticking out of the wall.

The guy is talking about his house! , Where I work we manage 1500 Access Points across 60 sites globally...Some sites (Manufacturing/Distribution) have 300 Access Points and some only have 5 !

This is exactly how my house was left. All ethernet and coax from every room returns to a small box in the utility room. Nothing terminated and all squashed in by the builder.

Expect a complete mess and a days frustration tracing and terminating each cable.

In a basic home setup, wireless has some plus points and convenience can be a major one. In general though, no. Wireless is open to too much interference. To get your full bandwidth, high end wireless stuff is not cheap. Wireless printers fall off the network all the time. Mesh systems play havok with ever more popular wireless soundbar systems.

The OPs house is already cabled so with some advise here he could have a fully connected network for very little outlay. OP, this reminds me of my brothers house in Royal Canal Park, all rooms were patched with no info and no sign of the central connection point in the house. We eventually found a bunch of cables in the utility stuffed in the dry wall behind an empty elec back box which was covered by a blank face plate - shameful job by the builders tbh. Anyway, it turns out the ports in each room were not actually terminated properly and obviously the bunch of cables in utility needed a patch panel or some ends put on. Guess what was my job on my last visit?!

OP, yeah, get your tool kit :) , check behind that faceplate at the front door - my guess, ISP router may have to live there, easy external access and you can then feed the connection to your central point. Any other blank faceplates in the house? Is there a utility?

If you're just building, I would put at least 1 port in each bedroom (I'd run 2 cables even if only connecting one port, stuff does break). Then a bunch, maybe even as many as 4+ in main entertainment areas for Tv's, set top boxes, consoles, sound systems etc. etc. . . . The cable costs next to nothing and they'll be running elec wire anyway so it's simple to pull along with it - a pain to do after building is finished! Even if they just run the cable, leave the terminating up to yourself as a little project, a few youtube videos and it can quickly be learned.

As @jacko says above, a few ceiling runs for potential AP placement is a really good idea whether you go for ports in the rooms or not.