When going from, for instance, 5x7 to 8x10, it might not be noticeable. Even if it is, it might not be objectionable but, if going from 4x6 to 11x14, I usually lose at least a grade of contrast. (Reverse if going from large to small.)
Again, it's not always noticeable or objectionable but it does happen often enough that I have to be aware of it and check for it. If not using an Analyser or some kind of meter, all it takes is a test strip to solve this. If using an Analyser or meter, all you need to do is double check but 9 times out of 10, it comes out right because the device makes that adjustment for you in the process of re-metering.