there are many, many other ways!
I use two primary methods, one that's a lot like how George Benson holds his (which is very natural to me, and my default), and more traditional, wherein the pick is held between the thumb and the side of the first knuckle of the index finger (more natural for most people).
I find the two grips are good for different types of facility, and I switch between them as a drummer might switch between traditional and matched grip.
In the 'typical' way, which I had to learn 'on purpose,' the pick angles downward. In the "Benson" way, the thumb is double-jointed and cocks backward somewhat, and holds the pick between the thumb tip and the pad of the index finger, and "locks" into position in the crook of the bend of the index finger's first knuckle. This causes the pick to angle backward, or upward.
Now. That's only one axis.
Many players will have the most success also angling that WHOLE thing downward, so that the heel, or rounded part of the pick, points toward the floor. That makes all downstrokes effectively "rest strokes," where the pick is stopped be the next higher string, and all upstrokes are effectively "free strokes"-- the angle means that on the upstrokes, the pick is dislodged from between the strings and flies "out," sort of.
A minority of players will do the opposite-- they'll angle the whole thing UPWARD, with the round part of the pick pointing toward the ceiling. That makes all downstrokes "free strokes," and all upstrokes "rest strokes" as the string comes to rest on the next fattest string.
With the downward pick-slanting, sweep-picking from low to high is very natural, and sweep-picking from high to low is very cumbersome. With upward pickslanting, sweep picking that goes from high strings to low strings is very natural, and downward sweeps are cumbersome.
Consequently, yet another minority of players will change the angle of their pick depending on which direction they are going across the strings-- sort of a hybrid pick-slant, so to speak.
But this is still not the end of the variables.
I also use my right hand fingers in addition to the pick, known as "hybrid picking." This allows me to strike four-note chords simultaneously, as opposed to strumming (where the notes are never truly simultaneous). Many country players and some others use the hybrid approach to give a certain type of linear facility, almost like a banjo player.
But it doesn't end there. We could keep going, and going, and going, and going.
But there are certainly more than two basic approaches!