I won’t speak in absolutes, but one of the great things about starting a career in IB is the foundational nature of the skill set it teaches. Most analyst programs include formal modeling, credit and financial accounting training. The actual responsibilities of an analyst also instill a familiarity with numerous other business disciplines.
Depending upon the specific area in which the junior banker is deployed they will often gain specific non banking industry expertise.
For most “arm’s length” (PE, HF, Financial Sponsor, etc) career pivots, no MBA is required and the numbers of those returning to school is dwindling. For many other (if not most), careers the combination of an undergraduate business degree along with IB training and perhaps CFA are more than adequate to pivot.
Obviously exceptions exist if going into a totally unrelated area but those exceptions are becoming farther and fewer between in my experience. I don’t see a lot of I bankers going back for MBAs while I do see a lot of undergraduates (primarily from non target schools) extending their college experiences by a year to get an advanced degree in the hope of improving their job prospects.
For purposes of this thread and this OP either school will likely prepare your child for an IB career and likely limit their needing an MBA down the road if their ambitions change.