journalctl(1) in systemd 234+ supports `--output=short-iso-precise` option.
```
$ sudo journalctl --output=short-iso-precise -t kernel -S today |head
2024-01-21T00:00:01.070536+09:00 sugar kernel: audit: type=1400
audit(1705762801.065:10307): apparmor="DENIED" operation="capable" class="cap"
profile="/usr/sbin/cupsd" pid=1358071 comm="cupsd" capability=12
capname="net_admin"
2024-01-21T04:09:57.478547+09:00 sugar kernel: PM: suspend entry (s2idle)
2024-01-21T04:09:57.482546+09:00 sugar kernel: Filesystems sync: 0.000 seconds
```
Regex "^(\w{3} [ :0-9]{11}|[0-9T:.+-]{32}) " matches it.
--
-- Name: SATOH Fumiyasu @ OSSTech Corp., Japan (fumiyas @ osstech co jp)
-- Business Home: https://www.OSSTech.co.jp/
-- GitHub Home: https://GitHub.com/fumiyas/
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