Mounting /tmp as tmpfs on Ubuntu 20.04

I'd like to mount /tmp without fstab entry using tmp.mount

However on Ubuntu 20.04 LTS, it doesn't seem to work.

user@user-x1:~$ systemctl status tmp.mount 
Unit tmp.mount could not be found.
user@user-x1:~$ sudo systemctl enable tmp.mount 
Failed to enable unit: Unit file tmp.mount does not exist.
user@user-x1:~$ sudo systemctl cat tmp.mount 
No files found for tmp.mount.
user@user-x1:~$ cat /usr/share/systemd/tmp.mount 
#  SPDX-License-Identifier: LGPL-2.1+
#
#  This file is part of systemd.
#
#  systemd is free software; you can redistribute it and/or modify it
#  under the terms of the GNU Lesser General Public License as published by
#  the Free Software Foundation; either version 2.1 of the License, or
#  (at your option) any later version.

[Unit]
Description=Temporary Directory (/tmp)
Documentation=https://systemd.io/TEMPORARY_DIRECTORIES
Documentation=man:file-hierarchy(7)
Documentation=https://www.freedesktop.org/wiki/Software/systemd/APIFileSystems
ConditionPathIsSymbolicLink=!/tmp
DefaultDependencies=no
Conflicts=umount.target
Before=local-fs.target umount.target
After=swap.target

[Mount]
What=tmpfs
Where=/tmp
Type=tmpfs
Options=mode=1777,strictatime,nosuid,nodev

[Install]
WantedBy=local-fs.target
user@user-x1:~$ 

What's happening? Why does systemd say unit could not be found even though bash auto tabbing fills up tmp.mount and what's the simplest way to enable this tmpfs without any config?