Architects for the most part design the facades and the interiors, the floor plans, pick out the fixtures and colors, etc., the overall concept and look of the building. But it is the structural and civil engineers who must find a way make it all work.
Structural and civil engineers must put their stamp on the structural design and the structural build drawings. Engineers would have been the ones to design how the building was anchored to the ground, how the pillars holding up the building were constructed and of what materials, and the underground structures such as the underground garage, calculate the slope of the pool deck to accommodate for drainage, waterproofing, etc.
There is an interview of the architect/engineer of the WTC made soon after the collapses. Good to watch.