I have been trying out Helix as my daily editor and the editor has built in support for LSP. However, it does not install the Language Servers, so you have to do that yourself.
Below are the language servers I installed for writing my code in HTML, CSS and Markdown.
You can always check if a language is setup by doing:
hx --health <lang>
So for example this will tell you if your HTML is supported:
hx --health html
HTML, CSS and SCSS
Both HTML, CSS and SCSS use the language server from Visual Studio Code:
npm i -g vscode-langservers-extracted
Markdown
For Markdown it uses marksman and to install it you can download the latest version from their releases page
wget <link from releases page>
# Make it executable
chmod +x marksman-<dist>
# Move it to a directory in your path, in my case `~/.local/bin`
mv marksman-<dist> ~/.local/bin/marksman
Move it to somewhere in your $PATH and you should be good to go.