At Ds school kids can take just a few IB classes or go all in for the whole diploma. IB can also take any AP classes they have room for on their schedule.
As far as the workload, I’m not sure. IB totally clicks with my kid so even though there is a lot of work I will say it doesn’t seem like nearly as much busy work as the AP classes her friends are in. For at least two of her classes, there is no graded homework, rarely a quiz. They have major papers due and tests. No homework and no assignments of handwritten notes (i.e. APUSH) means she is free to actually learn the material–which is more like real world college IMO.