nvim2023/after/plugin/ufo.lua

vim.o.foldcolumn = '1' -- '0' is not bad
vim.o.foldlevel = 99 -- Using ufo provider need a large value, feel free to decrease the value
vim.o.foldlevelstart = 99
vim.o.foldenable = true

-- Using ufo provider need remap `zR` and `zM`. If Neovim is 0.6.1, remap yourself
vim.keymap.set('n', 'zR', require('ufo').openAllFolds)
vim.keymap.set('n', 'zM', require('ufo').closeAllFolds)

-- Option 3: treesitter as a main provider instead
-- Only depend on `nvim-treesitter/queries/filetype/folds.scm`,
-- performance and stability are better than `foldmethod=nvim_treesitter#foldexpr()`
require('ufo').setup({
  provider_selector = function(bufnr, filetype, buftype)
    return { 'treesitter', 'indent' }
  end
})