No our lemons around here can get pretty big but not that big. I don't know if you can tell but its bigger than my hand in one of the pictures and has a slightly pinkish orange tinge on one of them, the riper of the two.

Unfortunately our lemons around here look like they have bumpy yellow tumors all over them. There must be a wasp or some kind of insect in our area that loves to embed into their skins which can cause the bumpy deformities.

But I can see from the cluster of grapefruits in the tree how you might think they were lemons. Thanks for your question hope this helps.