Hello,
not by regular means, as far as I know.
The problem is that the steps in the corners have a different depth than the normal rectangular ones.
You might try the semi-spiraled staircase tool. There is one possibility to set the angles of single steps. Another option there is to insert pedestals, but I do not think you can specify any size you like for this. The pedestals are calculated from the sizes of the normal steps.
The only way I see is in a first step to change the geometry of the staircase so that the semi-curved part needs exactly five steps of the regular tread and then adjust as explained.

Best regards
Stefan

Because this staircase is said to occur so often in southern europe, I took the trouble to construct the staircase manually. (see spanish_stairs.png)
With result you can see clearly, which problems at the stair eye develop, if there 3 step front edges meet at a point! At these points the virtual plate of the staircase runs vertically! I can not imagine that the builders in Southern Europe build such a "fidget" at the bottom!

The staircase would not be allowed to build in Germany, because this violates the DIN 18065 building stairs. The tread width must be the same for each step measured at the tread line! In addition, the tread width at the stair eye must not be less than 10 cm!
This are also the reasons why you can create such a construction (currently not yet) with the stair modeler.

You should not underestimate the safety of walking on the stairs. Around 4,000 people die every year in Germany due to accidents on stairs. That is almost 20 percent more deaths than in traffic accidents.
You don't want to have to appear in front of the judge because you've planned some shit like that!

Hello Jörg,

Of course, it was a joke...
One can work seriously and occasionally make a humorous wink.

You criticize the constructions of the Southern European countries and bring a judgment on the work of these countries. I have already heard this kind of thing.
I don't think there are more stair accidents in France, Spain or Italy.
The climatic conditions, the history, the traditions have shaped the building techniques of each country. Nothing is ridiculous. Everything can be explained. It is the richness of the different techniques that allows creativity in architecture. The most important thing is that the buildings are pleasant and comfortable for the users. The technical solutions and norms are working supports and safeguards.

...interessant wäre hier eigentlich, was die örtlichen Normen über Treppenkonstruktionen aussagen...

As already written, this staircase was constructed manually:

For the substructure, it was done as follows:
1. construct edge lines
2. create surfaces from it
3. join the surfaces to a body