Right.
There are three sexes: Male, Female, and Intersex.
Intersex are people with both both male and female sex characteristics. Typically they self-assign themselves based on the predominant sex.
It’s uncommon, but if you’re talking about 8 billion people in the world, there’s tens of millions of them.
There are not three sexes; there are two.
“Intersex” people have some type of phtsical malformation, usually resulting from genetic or chromosomal problems. This does not make them a third sex.