The section indicates that there is a wooden beam ceiling between the ground floor and the upper floor, and thus all those walls that continue into the upper floor are indeed "load-bearing."
According to the representation, the basement ceiling is made of concrete. This should allow the wall remnant to support a steel beam as intended. However, I anticipate the necessity to initially make the opening wider and to rebuild under the beam's supports with KS.
An alternative could—depending on the importance of this wall (on the upper floor) for the roof structure—be to also demolish the wall on the upper floor and rebuild it as a lightweight wall. That means, if necessary, practically: consulting a carpenter on how to support the roof structure down to the basement ceiling. This can influence the location of the desired opening.