FTPlugin (filetype plugin)

Description

From :h ftplugin

A filetype plugin is like a global plugin, except that it sets options and defines mappings for the current buffer only.

Example for setting specific shiftwidth and tabstop that only apply for C file-types.

-- create a file at $LUNARVIM_CONFIG_DIR/after/ftplugin/c.lua
vim.cmd("setlocal tabstop=4 shiftwidth=4")