Who's your favorite musician?
Miles Davis? Mozart? Elton John? Taylor Swift? Keith Jarrett? Ed Sheeran? Henry Threadgill? Bob Dylan?
One of the best ways to learn more about them and understand their music better is to compare their early, middle, and late styles. (Or, if they're still relatively new, their early and newer styles.)
Let's take Miles Davis:
How did he sound when he was first starting out, playing in Charlie Parker's quintet?
And then how was his style different, when he led his classic 1950s group with John Coltrane?
Taking it further, did he sound different in the 1970s-80s?
How did his trumpet sound evolve over the years? Was it related to the sound of his speaking voice? Did he play longer or shorter phrases at different times in his career? When did he start using the harmon mute? Did his choice of material change or stay the same? Did he use swing 8ths all the time? What was the role of his bass players in different decades?
You can ask similar questions about any musician you like. Dig deep, compare and contrast eras, and see what you discover!