I don't think that the queen can go much beyond the size of the others, she can just keep that size for longer than the others. Tbh i think that some guardians like Regina and maybe Maryen can grow just as tall.
Let's see
Nyxmay says :
ny "I couldn't stop the heart of someone who is more powerful than me."
ny "And I'm not the strongest giantess in Homaspernia, Yakuu and Pyeka are the guardians of this kingdom."
ny "Ah... but I could also do something good. Like I do when I make you feel less or none pain."
maryen
m "Can all giantesses grow?"
ma "Not all giantesses can grow, in fact, just a few of us have the power to do it."
ma "For example, all Guardians can grow. It's usually a requirement to become one."
ma "The Queen chose us to keep the balance and protect our kingdoms, so we are chosen more or less equally powerful."
m "You are not only protecting your own kingdom, but also places outside from your territory."
sh "She is the queen of all kingdoms on this continent."
sh "Every kingdom has their own human-sized king. They have their own laws and certain independency."
sh "But when I mention ''The queen'' I mean the supreme queen, a giantess even more powerful than the guardians."
sh "All guardians, Maryen included, are not only devoted to their respective kingdoms, but must also obey the supreme queen."
sh "Hmm... almost all giantesses have the same natural size as me."
sh "The most powerful ones can change their size and become way bigger."
sh "But since it consumes magic energy, we usually keep our natural size."
sh "Queen Orphelith have so much power that she could comfortably keep that size forever."
sh "When the situation requires it, she shrinks to her natural size, which is the same as mine."
sh "But what you just seen is just how she usually is, she can become even bigger."
sh "Other powerful giantesses can reach that size too, or even bigger. The guardians for example."
m "Are you telling me that Maryen can grow that big?"
sh "And also due to the fact that Orphelith is the most powerful giantess from the continent."
sh "Another important change that the queen brough is ''the guardians decree''."
sh "To help keeping the kingdoms safe, not just from foreign hostiles but also from the monsters and criminals that live all over the contient."
sh "The queen chooses two guardians from every kingdom. A main and a second guardian to be more accurate."
sh "Those guardians are very close in power and strength to the queen."
sh "The immense power of such guardians not only helps protecting their kingdoms."
sh "But also reduce the number of war declarations, due to the fear of a massive annihilation in both sides of the conflict."
Basically: Queen Orphelith can remain enlarged indefinitely due to her immense power, but she can also shrink to a natural size when needed. The guardians are weaker, but not by that much.
