There are a few customization options that are specific to the Nextstep port. For example, they affect things such as the modifier keys and the fullscreen behavior. To see all such options, use M-x customize-group <RET> ns <RET>.
The standard Mac / GNUstep font panel is accessible with M-x ns-popup-font-panel and will set the default font in the frame most recently used or clicked on.
In macOS, Emacs uses a Core Text based font backend by default. If you prefer the older font style, enter the following at the command-line before starting Emacs:
% defaults write org.gnu.Emacs FontBackend ns