The LSP support itself is builtin in Neovim (not in Vim though, AFAIK), but each language server needs to be configured and activated. There is a plugin with all(ish) configurations - https://github.com/neovim/nvim-lspconfig - and activation is done with a vim.lsp.enable("server-name") command, which you just put in your config and the Neovim will start the LSP when you open a relevant file.