Generate random shape like this

hello, I am a beginner and I was wondering how do I generate shapes like these (one at a time) that are inside a quad grid of size b6 x h8 and a cell size of 3mm? the size of the grid can also vary, the important thing is that the shape remains inside.

You must use a planar quad mesh
Explode it
Choose some of the faces
Merge the faces
Then apply Catmull Clark subdivision


but I have to make sure that the squares are all connected to each other with at least one vertex. and at the points where two vertices are connected a connection is formed, and all the connections must have the same radius, that is half the side of the single cell.
I hope to have been exhaustive.
thanks a lot for the help

See that also

You could also use clipper offset to round the shapes. Offset in one direction then offset in other direction (negative)
And try experiment fail retry …