So I've only read probably 15 or 20 King books... which would be A LOT if you're talking about literally any other author. :)
He has this 8 book series called "The Dark Tower" which is phenomenal, but it ties together all of his books in a kind of "Steven King Universe" kind of way.
You can read it by itself, but when you realize there are all these hooks that tie into The Stand, and It, and Salem's Lot, and Insomnia... well, you get more out of all of it.
The Gunslinger
The Drawing of the Three
The Wastelands
Wizard and Glass
King's Car Accident
Wolves of the Calla
Song of Susannah
The Dark Tower
The Wind in the Keyhole
I separate out the two halves because, frankly, if I'm being brutally honest... the last 4 aren't as good. I think facing his mortality scared him and while he paced the first 4 books about 5 years apart (that cliffhanger ending on book 3 was a 5 year nightmare!) he really rushed through the rest of them and it shows. 😢
Dark Tower related, in the order I'm remembering them:
The Stand
It
Rose Madder
Insomnia
Desperation
The Regulators
The Talisman* - Not really, but the sequel ties it in.
Black House - Sequel to the Talisman that ties both to the Dark Tower
Talisman 3 - upcoming book. This year?
Salem's Lot
The Shining
Doctor Sleep
Eyes of the Dragon
Hearts in Atlantis
Fairy Tale* - Not really, but close enough!