What breed/sex are these chickens? Help!

[ZombieShrimp]

Bought these four chickens at Tractor Supply on August 22, 2023 from the ISA Brown pullet chick bin. Thought we were getting all pullets since the bin was labeled pullets and from what I have read ISA Browns are sex linked or color linked. The problem is that two of the chickens are much larger than the other two. The two larger chickens also have thicker legs, are much darker in color, have larger combs, annnd we have in the last few days heard what sounds very much like a rooster starting to test his crowing out in the morning. We haven't spotted which one of the four is doing the "crowing" yet but it seems likely that it is one of the larger darker ones. Though the two darker ones are not what I have seen an ISA Brown rooster look like, I am questioning if they are roosters that were of a different breed and mistakenly put into the wrong bin? I have attached photos of when we first brought them home, one from a few weeks ago, and from just a few days ago. On November 11, 2023 it will be 3 months (12 weeks) since we brought them home. Also, I apologize for any wrong terminology...this is our first time owning chickens! Any assistance in identifying breed and sex will be very much appreciated! If I need to include any information please let me know. Thank you!

 

[Holdthechicken]

Both of the darker ones are cockerels. I’m not sure what they are, similar to rhode island reds, but my littles weren’t that white as babies so I’m not sure.

 

[ZombieShrimp]

Both of the darker ones are cockerels. I’m not sure what they are, similar to rhode island reds, but my littles weren’t that white as babies so I’m not sure.

Thank you for such a quick reply! That's very helpful and I believe is confirming my suspicions haha. If it helps any...there was a bin of Rhode Island Reds (straight run) right next to the bin of ISA Browns (pullets) that we picked from. There was also a bin of Bantams and a bin of Black Australorps.