config.nvim/lua/plugins/nvim-ts-rainbow.lua

require'nvim-treesitter.configs'.setup {
    rainbow = {
        enable = true,
        extended_mode = true, -- Also highlight non-bracket delimiters like html tags, boolean or table: lang -> boolean
        max_file_lines = 4096, -- Do not enable for files with more than n lines, int
        termcolors = {"red", "yellow", "green", "blue"} -- table of colour name strings
    }
}