A High C is a C6, a soprano C. I guess they call it a Soprano C because (trained) Sopranos should be able to reach it no problem. It's one of the highest head notes you can reach and difficult to pull off well. It's iconic in opera.
Here are some examples of perfectly executed High C's
Beyoncé's headvoice is RICH, she can go as high as E6 (she can actually reach F6).
Here's her famous Emotion high C that left Celine Dion in awe
The resonance and power
Here are some of Bey's most recent (studio) high C's in Bow Down and ***Flawless
Here she hits a C6 live and goes even higher and hits a D6 @ 0:58
Favorite showcase. Here she hits several C#6's (a semitone higher than C6) @0:27 and then hits several Eb6's! (which is a semitone higher than a D6)
Beyonce's voice is absolutely amazing. Really. She doesn't get enough credit. I'm not a huge fan of her tone, but her control and technique are just beyond!
Well you've established that Beyoncé can sing C6. Janet and Aaliyah are both trained sopranos so yes they can. Janet sang a C6 in "Love Will Never Do (Without You)". I've heard Aaliyah's high C but I don't know the name of the song.
I'm a baritone and I can strainsing and E6. My soprano C really sounds a mess. It's not stable. It's powerful (or maybe just loud as ****), but uncontrolled. I can't create a vibrato without losing the pitch. But HEY, it's there. How many deep-voiced men can say that?
