Carlos Alcaraz is one very special tennis player and you only need to inspect some stats from his rather young career to see it.
You don't really have to know tennis history in depth to understand how special Carlos Alcaraz truly is. The fact that he's being mentioned regularly among the Big Three is proof enough that his stuff is that of a special type.
Alcaraz, in many ways, does resemble the Big Three because the things he's been able to do so early in his career are not the norm. There are very few tennis players who did that, which is easily demonstrated through various milestones.
He's the youngest number one ever on the ATP Tour, which is incredible, he's also the 5th youngest to ever win two Grand Slams. The second one happened recently in London as he defeated Novak Djokovic in the Wimbledon final to get it done.
Only Mats Wilander, Boris Becker, Bjorn Borg, and Rafael Nadal were younger in achieving that, and he can further that legacy if he wins the US Open. Alcaraz, of course, won last year's US Open which certainly puts him in contention for this year's event.
If he does that, he'll be only one of four men ever to win three Grand Slams before the age of 21. That's significant as that list doesn't feature players like Novak Djokovic and Roger Federer, proving how hard it is. It would also confirm that he truly is on the trajectory to win 10+ Grand Slams in his career, which would put him quite high in the Pantheon.
Some have even suggested he's capable of becoming the greatest ever, and while it's possible, talks about that are quite premature. Let's enjoy his wonderful tennis skill for now and let the future unfold as it will.