Now that I know they’re technically still babies that makes it harder, especially because they still have baby voices, their voices will deepen in the next few months and it will be easier to tell between male and female voices. Ganders will have a much louder honk, females will have a deeper chatter.
The largest seems like it could be a gander to me, it is noticeably larger and taller which is more typical to ganders, I had one enormous female once but usually girls are smaller. Ganders also tend to be more willing to stand between you and the female(s).
The smallest looks like it could be female, it behaves more like a female, though they’re still young at this point so it’s hard to say.
The other could be a more dominant female, “I have a few of those” or it could be male.
At this point it looks like you have one gander and two girls but like I said, it can be hard to tell until they’re older.
All I can do I guess is compare them to geese I have and have had.
I had one enormous female, she was taller and heavier than all but one of my ganders, she was a fluke I think so it’s possible but more rare to get a super sized girl.
Of the geese I have now the ganders are always taller, some of the ganders are taller than the others.
I have two ganders and two girls about the same age as yours, the smaller of the two gander goslings “Roxberry” is the most dominant and bossy of the two boys, and the other “Helios” is already the tallest in the flock, but he’s also the most docile goose I’ve ever known, his sisters are feistier than he is so temperament isn’t always an indicator of male or female which can make things confusing.
Of the girls one is very shy and likes to keep out of everyone’s way, but her sister is bold and always investigating everything and everyone.
I hope this information helps you determine who is what in your flock.