I would say it's quite uncommon, although it does seem like the recruiting cycle is getting earlier and earlier each year. Most consulting firms don't offer freshmen summer internships, so the best you can hope for at that stage is to get a sophomore summer internship.
I don't know how this person you are describing got the internship, but my guess would be that it involved a lot of networking, and/or personal contacts.
If you were interested in something similar, your best bet would likewise be networking: attending industry events, or reaching out to consultants on LinkedIn/email (politely, expressing interest).
However, bear in mind that freshman year is very early to be thinking about consulting internships! As mentioned, most firms will not have established internship pipelines for freshmen, and will expect you to take more time to explore potential career pathways before you conclude that consulting is the right option. So don't be discouraged if it seems like there isn't too much you can do at this stage - you are very much ahead of the game in thinking about this, and will see many more opportunities open up in the next few years!