I've never propagated Magnolia x alba myself, but why would it be different from any other magnolia?

I'd be very tempted to go in that direction.

i read it online, no one has suggested to use cuttings to propagate this plant.

And I'm recommending that you treat this particular Magnolia just as you would any other. I don't think that there is anything special about it that would preclude asexual methods of any kind.

I see 'white champaca' also listed as Michelia alba. Perhaps you will find information cited under both of names...Magnolia alba or Michelia alba.

According to my research, it rarely sets seed in the garden and propagation by cuttings is essential. Softwood or semi-hardwood timing is suggested.