If you only read one Doctor Doom-related comic to get to know the villain and what he might be like in the MCU, I would recommend legendary Marvel writer Jonathan Hickman’s run on the character. This is cheating though, as Hickman built up his take on Doom starting in 2009 on Fantastic Four and ending in 2016 with the conclusion of the Secret Wars event comic. That’s roughly seven years of comics to read, which is daunting, though I promise it is worth it.
Across Fantastic Four, Avengers, New Avengers, and Secret Wars, Hickman’s portrayal of Doom as a man who works on the highest level possible in the universe is fascinating. He’s basically playing 5D chess at all times, and watching Doom concern himself with the end of the multiverse and the killing of gods, essentially on his own, is badass. 2027’s Avengers Secret Wars bares the same name as Hickman’s climactic finale, so you can bet it’ll be a major inspiration for the MCU.