If nothing can escape a black hole, how do they get bigger in size?

In order for the size of a black hole to increase, surely there must be some resistant force within the black hole pushing out?

My thinking is that in order for object A to be physically larger than object B, there must be more layers to object A that are being repelled by electrostatic forces so that they cannot collapse into themselves, like layering rubber bands on a ball.

But if black holes collapse to a point of infinite density, how do they "get bigger"? Is it instead the case that black holes do not "get bigger" physically, but instead, because there is more stuff within their singularity, the reach of their gravitational pull is further, making them seem "bigger", when in reality a small black hole and big black hole are the same "size" (a singularity) with differing gravitational reaches?