One out of three Pixar films has used an established IP, so we can say two-thirds are originals!To be fair the actual animated film slate is fairly original as far as the last decade is concerned.
All the Disney Animated movies are original and arguably Pixars' one aberration out of four they showed is not a sequel/prequel either.
While Walt Disney Animation Studios normally eschews sequels, they have succumbed in the past: Rescue Ranger Down Under, Ralph Breaks the Internet, Frozen 2, and two Pooh movies.
Of course, While WDAS didn't normally do sequels, the DisneyToon was usually handed the job of cranking out Direct-to-TV lower quality sequels.
The funny thing is that we have that again: Direct-to-TV. That's what Pixar and WDAS (not DisneyToon) are doing with creating Disney+ series, most of which are indeed based on pre-existing IP.
Anyway, it should warm a sequel-haters heart to know that these original animated features are coming from WDAS and Pixar: Soul, Raya, Encanto, Luca, and Turning Red. The only theatrical IP recycler is a Toy Story prequeal: Lightyear.
No mention of 20th's Animation of "Ron's Gone Wrong," hmm...