Are LAN sockets still up-to-date? WLAN/wireless is the future!

No. Nowadays you basically can't get anything below Cat 6 anymore and that is more than sufficient.

Ok. Super. Thank you. The whole thing is a terrible topic for me and I am actually not interested because I have little need in that direction. We don’t game and haven’t built smart either. Not our interest. But one should not completely close oneself off to the topic. But I think I almost understand it. I’ll know more in a month at the latest.....

Why are you doing that yourself then? ;-) The electrician will be able to take care of that for you.

For me, the raw cable without a connector sticks out of the wall. [...] The cable is still without a connector. What is the difference if I (have it done) directly attach an RJ45(?) connector there

You also have the problem of not having an infinite number of attempts to correct your work if it fails.

Patch panels have sockets only on the front because they are only accessed on the front (patch side) with flexible, pluggable cables. Installation cables are stiffer and connect the patch panels on the back via fixed holders (e.g., LSA+ terminals). If you consider as an "alternative" to bring a cable "logically from the network side" but "physically from the patch side," be given as a "figurative idea for understanding" that it would be like if a power cable came out of the wall not in a box but with a socket face. A patch panel (or also a VVDo) always has "two sides of the coin": the provisioning side (network) and the distribution side (patch). Whoever already has a node of confusion in their head should hereby be absolved that it is not shameful to also commission a professional. A (particularly important for laypersons) major difference between the network and patch side is that an installation cable (already laid through the house) is "finite" and gets shorter with each failed DIY attempt, whereas a patch cable—unless purchased pre-assembled—can still be used as a shorter patch cable or exchanged for small amounts of money.

Do you need an extra cable to operate the access point with PoE? Are there differences, or what do I have to consider regarding the cable?

For PoE as well as for Gigabit, you need "fully wired" cables—but those that are unusable here are usually clearly marked with the "warning" "ISDN" ;-). PoE means "Power over Ethernet" and specifically means that NO additional power cable is needed, but the voltage is transmitted over the data cable.

The electrician was also the one who just let the cable stick out of the ceiling. In my opinion, he should have advised me better when I told him that I was planning an access point there. But that’s not a big deal. I’m trying to learn and understand as much as possible and therefore want to do it myself. But not blindly. First, I ask about possible solutions. Then I try my hand at the execution. I have also never laid tiles before. Yesterday I finished the first room by myself (a small basement room). I just want to use the house construction to gain new skills. And since my skills regarding networks are rudimentary, I am trying to learn through your tips. But of course, if I (preferably early on) realize that I will probably fail, I will call in a professional. Otherwise, it doesn’t make sense. But overall, thanks for the helpful information. Even though I had to read 11ants’ text three times to understand it :-)

Great setting! I do it the same way. Also with the tiles :D

The fact that you're gathering information here and have already landed on unifi solutions gives you a huge leap in knowledge. You're ahead of where I was 2 months ago, and I'm at home in the IT industry :D