Beware that not all of them unlock content. I found 2 or 3 that didn't gave me any return...and found some yellow ones that helped a lot with world building.
Maybe you want to follow this link: https://ffxiv.consolegameswiki.com/wiki/Content_Unlock
Or this one if it's your first time: https://ffxiv.gamerescape.com/wiki/G...Locked_Content
Still, i wish we had a "Journey Guide" in-game.