Which router for our new building?

Do you always repatch because the switch is too small?

Basically, yes, that's what patch panels are for, as has already been said here.
When I buy a new (current) PC or TV, patching is the smallest problem.
I have double sockets almost everywhere, but most of the time only one device is connected in the sockets.
For example, the TV with media receiver. Why should the TV also be connected if the receiver does all the work and can do everything?

Regarding counting ports: For example, I currently have the AVR in the basement because I can’t connect and operate it here. In the new building I want to do that (again). For that I need a connection that I don’t currently have. That’s how I approached the planning. Unfortunately, due to the restrictions in the transition apartment, I’m not using all the devices, but the connections for them were planned in the house. The planning was in 2021, so a few days ago. Now, for simplicity, I counted ports instead of going through all my hardware, which is now stored with relatives. I just hope it doesn't walk away.

An AVR is just one device after all.
But okay, maybe you have many of them?

And yes, my wife downloads recipes with the kitchen machine (or does whatever with it). It’s the Lidl one.

Such devices go into the WLAN.
It’s ugly and impractical to have network cables lying around in the kitchen.
Although the main reason is probably that such devices don’t even have an Ethernet port. ;-)

I’m curious now:
How many connections have you planned and how many do you get by with?
About us: 4 people, 6 rooms (without basement/storage rooms), 2x home office, no smart devices.

That info probably won’t help you much.
But normally it’s something like 4 PCs (although laptops are mostly only on WLAN), 2 TVs with receivers, AVR, console?, router, wallbox?, inverter?, NAS?: With some question marks this adds up to 14.

But if you don’t have other requirements regarding management etc., affordable and energy-efficient 24-port switches are definitely an option.

Interested me now: How many connections have you planned and how many do you get by with?

I have about 28 connections distributed in the house. Currently, 4 of them are in use: router, access point, PC, laptop docking station. The server is connected directly in the network cabinet, FireTV over Wi-Fi is completely sufficient. Someday all the kids will have devices, then there will be more. I would do it exactly the same way again.

And yes, my wife downloads recipes with the kitchen machine (or does whatever with it). It’s the Lidl device.

Such devices connect to Wi-Fi. It’s ugly and impractical to have network cables lying around in the kitchen. Although the main reason is probably that these devices don’t even have an Ethernet port. ;-)

Since when does the Lidl Thermomix have an RJ45 network port? As I said, I’m still looking in vain for large kitchen appliances with fixed LAN cabling. I have to be honest, I don’t care a bit more about power consumption if I don’t have to constantly worry whether a network socket is connected or not. There are completely different saving potentials in the house.

How many devices do you have active? Do you always re-patch because the switch is too small?

The other way around ...

I currently have 48 1 GbE ports planned for the house, that can be managed! Of those, 21 PoE devices are permanently active,

up to here two 16-port switches would be enough ...

16 ports come from duplex sockets in the living rooms (of which probably 6 are realistically used permanently).

and that would be 16 patch ports, but only six switch ports.

I have listed the optional connections separately. There is no "double allocation" here.

... so they will only need a home at the patch panel, and you can leave them out of the calculation at the switch entirely; besides, cordless end devices don’t need a patch port at all! By the way, you can also operate a kitchen machine separately, it will never want to communicate with many other end devices. By the time the kitchen machine gets the recipes in the live stream of the currently running cooking show, the equipment bought today will have long since been discarded. A basic understanding of network design "saves ports" :)

The other way around ...

Milan or Madrid? As long as it's Italy. Yesterday was a long day.

By the way, you can also operate a kitchen machine separately; it will never want to communicate with many other devices. By the time the kitchen machine receives the recipes in a livestream from the currently running cooking show, the equipment bought today will have long been disposed of. A basic understanding of network design "saves ports" :)

You are, of course, right about the kitchen machine; I was mistaken here; it is connected to Wi-Fi. I don't operate the thing myself, or rather, my kitchen appliance is a grill.

Again, please regarding the original topic of power consumption – this time without links, since I was warned.

[*]2 switches
[*]1 that is PoE capable
[*]1 that covers both connection options

Yes, one can of course argue about the right lever regarding power consumption, and usually it is individual user behavior that makes the difference. However, when I buy a new device, I do pay attention to that.

I do not operate the device or rather my kitchen appliance is called Grill.

I do not mean operate in the sense of typing on the keyboard, but in the sense of providing the services of the switch.

Yes, of course one can argue about the right lever when it comes to power consumption, and mostly it is the individual user behavior that makes the difference. However, when I buy a new device, I do pay attention.

That is why you should design your network so that on the one hand you do not oversize anything and "think" in terms of active and passively operated end devices, but on the other hand also avoid configuring segments in such a way that additional interconnect demand is generated. This is not a DIY field ;-)