Via in Kicad connecting multiple layer?
If you place a via connecting the capacitor to the IC's power or ground pin, KiCAD (or any CAD program) should automagically connect the via to the power or ground layer as required.  Even a short track and via from the cap's power or ground pin should be automagically connected to the appropriate plane.

Generally, any via on the same net as an inner layer will be connected to that layer.  There should be no special effort required to make that connection.