Pin size plot in IC layout

Whitout mentionind what kind of device, and how big, the question sounds a bit vague.

The large pin (port) size is potentially a very useful thing - using it, you can pass your design intent to downstream tools.
The "design intent" here is your knowledge or requirements, that the area under the pin shape (usually rectangular) should be equipotential, and/or that the pin shape is where connection to the upper (hierarchy) metal layers should be made.

Parasitic extraction tools have commands to "accept" that information, and short all the fracturing points (sub-nodes) under the pin shape.

Very often though, extraction tools will just place a single discrete point, where you place the port text label (equal to net name), and the information about the finite (large) pin shape gets lost.

Large size ports are important for power nets, for power FETs, and in some other situations.