Does increasing pack size modifier increase Rare monster count in maps?

Does increasing Pack size in a map via any means (eg, watchstones, sextant, corrupted mods etc) increase the number of rare monsters count in map?

If I have a map that has Monster Pack size +50%, does it means I have 50% more Rare monsters in maps?

If someone can explain to me what Exactly does increased Pack size do , that will be great.

thanks

most likely not. Rare packs seem to always have only one rare monster (unless there is a rare duplicate modifier present). You will get more magic and white monsters.