in order to get intellisense for tailwind on neovim using coc , I didnt use coc's tailwind package. I've used https://github.com/rodrigore/coc-tailwind-intellisense/issues/29#issuecomment-1000861947 . There is a problem with tailwind 3.0, that his posts tries to solve. It worked for me, installing global @tailwindcss/language-server and using that config on coc. for completion of :class "asd" I've used

"tailwindCSS.experimental.classRegex": [
  ":class\\s+\"([^\"]*)\""
]