I just bought The Witcher 3: Wild Hunt, and the DLCs The Witcher 3: Wild Hunt - Expansion Pass. When I click on games all I see is The Witcher 3: Wild Hunt. Where are my DLCs and how do I install and select them to play on PC Windows 10?

Check your listed games and check the offline installers, or use galaxy, they are there.

Just a curiosity, did you buy the game and DLC as separate products? If so I'm curious why you'd do that instead of just buying the GOTY Edition which is usually a bit cheaper and includes the game plus the expansion packs all in a single convenient installation that is fully updated.

Either way though you end up with the same game with no differences.

I didn't realize the GOTY included the Expansion Pass.

Back in the day GOTY usually meant some kind of "complete" edition... sadly that is not the case anymore, but for Witcher 3 it's true.

In fact if you bought the game and expansion pass, the GOTY should be automatically added to your account.

The expansions are listed under Witcher 3 main game, if you expand the "backup offline installers" of Witcher 3 they should be listed there as well. If you use Galaxy they should also be automatically installed along the main game.