This post shows how to set up multiple LSP's in helix, the example uses pyright and ruff-lsp for python.

Add this to your ~/.config/helix/languages.toml a

        
[[language]]
name = "python"
auto-format = true
language-servers = [
    {name = "pyright"},
    {name = "ruff-lsp"},
]

[language-server.pyright]
command = "pyright-langserver"
args = ["--stdio"]
config = {}

[language-server.ruff-lsp]
command = "ruff-lsp"
args = []
config = {}