I usually end up with a block very close to the intended size - with no starch/sizing added.
However, I do soak and wash my fabrics before cutting them - so that most of the shrinkage (if any) has been removed. I bought some 2-1/2 inch cut strips - washed them - they are now 2-3/8 inches wide. It is a Kaufman or Hoffman fabric.
Pressing with steam can - I think - also shrink fabric.
As far as I know, starching/sizing can shrink fabric - if it is going to shrink. Might be a reason to apply it evenly to the fabric and let it saturate the fabric. I am not an expert on starch/sizing, so -
I do consider myself knowledgeable about shrinkage - because I measured hundreds of cotton woven fabrics before and after washing them.