No, you need that plugin/script but installation and usage is rock-solid, I am using this now for years. FWIW, I also never use nvim's built-in terminal because

No, you need that plugin/script but installation and usage is rock-solid, I am using this now for years. FWIW, I also never use nvim's built-in terminal because this setup with tmux is so fast and feels super natural. Hint: you have to redefine more of tmux' binds, the defaults are just not usable. Hint2: most creation and resizing of panes and windows binds should be mapped without the tmux prefix, you can do this with "bind -n" in the .tmux.conf. Hint3: read the tmux manual, it's really good and on one (long) page.