Identifying a cast iron hub
Pull this out.

Charlotte Pipe 3-in x 2-in dia Reducer Cast Iron Fitting, Lowes
And put this in.

Fernco 3 in. Hub x Cast Iron Service Schedule 40 Weight Donut, ferguson.com
If it doesn't connect to a 90 degree elbow hooked to a wye laying on its side, it was done wrong in the first place. That's the only situation you should have to bust up concrete.