This is a helper package that automatically installs and updates the Svelte Language Server for you.
Open configuration file using command palette with Preferences: LSP-svelte Settings command or opening it from the Sublime menu (Preferences > Package Settings > LSP > Servers > LSP-svelte).
The typescript-svelte-plugin provides additional Svelte-related functionality in JS/TS files. To enable it, install it in your project and configure following its documentation.