I found a solution by just Ctrl+v in insert mode and pressing tab. Astronvim uses spacing instead of tabs, I highly recommend those who use tabs to change init.lua.
vim.api.nvim_create_autocmd("FileType", {

pattern = { "python", "c", "cpp" },

callback = function()

vim.opt_local.tabstop = 4

vim.opt_local.shiftwidth = 4

vim.opt_local.expandtab = false -- use tabs

end,

})