They are alluded to in various PCS categories.
https://www.isu.org/figure-skating/...96-program-component-chart-id-sp-2019-20/file
Skating skills: use of deep edges, flow and glide, rhythmic knee action (Kostornaia easily outshines Trusova in all of these, and IMO about on par with Anna, although Anna's edges and ability to gain speed seem more effortless than Alexandra's)
Transitions: quality - it's not just difficult but also the way you transition movements from one to another -- Trusova's transitions are a bit staccato/mechanical whereas Alena's are way more seamless.
Performance: carriage and clarity of movement - this is the biggie in terms of grace and elegance -- a skater with clearer, finished movements (vs a skater "going through" the movements) is a more aesthetically pleasing performance to watch - hands down Alena is the best at this, way better than either Anna/Alexandra)
Choreography: movements match the phrasing - this is part of "grace" - your body lines and finessed movements/hands/legs that bring out the character of the music; of course, Alena's ice coverage is the best of the 3, too
Interpretation: no contest here either against Alena who is for sure the best interpreter of the three; note the part about use of finesse to reflect details and nuances in the music -- clearly Alena is the best at this, and Anna's not great yet, but she's getting there; Alexandra still looks like she's been given a program and told to perform this step and then this jump and then this spin and final pose... she hasn't got it to a point yet that it feels authentic (again, in my opinion). It's a very hard thing to do, deliver a competitive skate with tough jumps while also delivering elegance/grace.
Energy and immediacy is good, because it shows "physical/emotional involvement" (under the PE category) to the performance, but substance tends to do better than flash. Maturity is of course subjective, and not always desired depending on the music. A more playful, energetic program is fine to show a bit of spunk and scrappiness, but when you're trying to deliver classical music or doing Game of Thrones, I wish Trusova would lend more attention to extension, and taking a moment to finish her movements. It still looks rushed to me, like she's just getting through it.