How do I exit the systemctl status command's output? [duplicate]

If you mean

systemctl status

at the end it shows this:

      ├─systemd-journald.service
         │ └─318 /lib/systemd/systemd-journald
         ├─fwupd.service
         │ └─1703 /usr/lib/fwupd/fwupd
         ├─systemd-networkd.service
         │ └─395 /lib/systemd/systemd-networkd
         └─cups-browsed.service
           └─2918 /usr/sbin/cups-browsed
lines 172-194/194 (END)

... then press a q for quit.

As steeldriver noted in comments: use --no-pager if you do not want this behaviour see details.

systemctl status --no-pager

Check what systemctl is running in another terminal:

$ pstree -pa $(pgrep systemctl)
systemctl,2100 status
  └─less,2101

And from man less:

q or Q or :q or :Q or ZZ
  Exits less.

systemctl status | cat does the job as well. You're just redirecting the output of systemctl status to cat which in turn dumps everything on the console without any pagination