What is the best way to break concrete under existing framing (2x4) to install plumbing?
You may have to adjust your ideas of what's needed to get this done.
You make sawcuts and drill holes as close as you can to the place you need to open, but it may well not be practical or possible to limit that to the particular room you want to work in, especially since you appear to be planning to run the pipe inside framing with drywall you don't want to disturb on the other side. Welcome to &quot;drywall repair is comparatively easy, and breaking concrete requires a degree of access.&quot;
Or you make your hole on the side you plan to access, watch Shawshank Redemption 12 times for inspiration, and delicately hammer and chisel your way under the framing, but no further. By which time you could have ripped the wall apart, bashed the hole open, and repaired the wall 3 times over, but it's your choice.
One approach, depending on exactly what you need to do and what you are willing to rent, is to use a holesaw (for the lumber) followed by a diamond core drill (for the concrete) to make the hole for the pipe, and just cut a hole in the floor on this side of the wall for access, that does not directly connect to the hole for the pipe.