Is it possible to have a window in the guest WC/guest room despite the garage?

How can the entire floor plan depend on the guest WC window?

I don’t understand either. An awesome design can also work with a guest WC without a window. But you could also think that it’s not such an awesome design if you have to shift the house and shrink the garage just to get something common.

In the past, houses were almost only built with raised basements, right?

In the past...

"people simply don’t do it nowadays"

would not be enough of an argument for me.
In the past, many things were still done in the basement, something the current prospective buyers hardly know anymore: furniture repairs on the wooden bench, laundry mangles, for hours. Seasonal swapping of many things like clothes and furniture. Nothing was thrown away. People often spent their working day down there. The flowers were not thrown away but brought into the bright basement.
Then the coal was dumped through such a window. And sometime after the coal stove era, people realized that times had changed and that the staircase in front of the front door and at the back to the garden was simply just crap and the basement was superfluous because you only had junk down there. :cool:
And for a granny flat or a recreation room, you need something more than just a basement window.

A completely different question, the 2.50m in your drawing, is that the room height when everything is finished or the raw construction height? If the latter, quite a bit of room height will be lost, which makes such a window difficult...

.....and where is the draft now??? Ideally filled out right away with the questionnaire AND ! real furniture measurements.

Here in the city, you can still often see high basements in the old coffee mill houses; visually, I find such a higher terrace great and yes, the basements are also a bit brighter because of it. But I wouldn’t have chosen that in a new building, simply because I imagine it too inconvenient in everyday life for various situations: Watching small children even more closely so they don’t fall down the garden stairs every three days because they run out too fast? Carrying groceries up a few steps to the front door (yes, I admit it, I’m lazy about that)? Having two stairs to the outside from the ground floor when you’re older? And then maybe even a more squat upper floor just for a slightly brighter basement? Personally, it wouldn’t be worth it to me. As for the window in the guest WC, I can understand that well, not only because otherwise it would be as dark as in a rental apartment but for obvious reasons you really want to be able to open a window there sometimes. Whether that fits dimensionally, your construction company/architect can surely tell you; we placed our guest WC in the same spot in the house but moved the garage to the back because I find “loophole windows” visually quite ugly and at 1.58 m I probably wouldn’t be able to reach them anyway :) So, in your place, I would either try to place a different room there (cloakroom, pantry, not often used office?) or move the garage. I don’t know your site plan but if it also applies to you: If we had only moved our house one meter west further away from the neighboring property and then chosen the mentioned “air corridor” between the house and garage, we would have saved ourselves a Berlin-style construction, quite some costs, and quarrels with the neighbors about cracks. My parents-in-law built it that way back then and I don’t know why it’s criticized here; I saw more advantages: sheltered shaded entrance, space for strollers, bicycles, shoes, flower decorations, etc.

Just a completely different question, the 2.50m in your drawing, is that the room height when everything is finished or the raw construction height? If the latter, quite a bit of room height would be lost, which makes such a window difficult...

I also believe that the height of the intermediate ceilings has not yet been properly considered. If you look at the sketch, there are exactly 20cm between the top edge of the basement window and the ground floor floor. That in turn means that the basement window with a height of 40cm starts right at the basement ceiling. It follows that if you want to be able to look out of the window, the basement ceiling height must be correspondingly low.

And that is exactly what was done in houses from the 60s. Much too low basement ceiling heights. I live in such a renovated house. My basement windows look exactly like in the sketch. Basement room height is 2.03m. I think my house and my basement are great, but I would never plan a new building like that!

oh yes: from the approximately 40cm high window opening you should also subtract the frames of the windows. I pragmatically installed standard windows that can be opened, so less than half remains for the glass pane. It could certainly have been solved better, but whatever at this point. I do not need daylight there.

The alternative would be to build an "air gap" between the house and the garage, in order to be able to equip the entire right side of the house with windows. However, this gap is often discouraged here in the forum.

Such a coincidence, I of course also have an air gap like that at my house. At the same time, however, there are no windows at all on that side on the ground floor. The view of a garage wall would be terrible anyway.

and then would have chosen the mentioned "Luftschneise" between the house and the garage,

What is a Luftschneise? Can someone explain it to me?