If you aren't using GNOME but for some reason want to use GNOME Terminal in other desktop environments (e.g. Sway or XFCE), you just might want to embrace client-side decoration (CSD), so it looks like this:
Unfortunately, CSD is not used by GNOME Terminal if you launch it outside of GNOME. Fortunately, there's a configuration option you can use to explicitly enable it. In order to do that just run the following command in your terminal:
$ gsettings set org.gnome.Terminal.Legacy.Settings headerbar true
Please note, the setting won't be applied as long as there's a running copy
gnome-terminal-server process. You have to terminate it and restart the
terminal. The configuration option is tested with
gnome-terminal 3.40. It
might or might not work with other versions.