It's a late reply, but might be of use to someone.
To output a formatted date using liquid, you'd use:
{{ 'now' | date: '%B %d, %Y' }}
That would get you 'February 28, 2024'.
Importantly there wouldn't be any timezone adjustments based on where the user is - though that's very possible if you need it.
I would ask though, what email client isn't going to show the date it was received? Is this an issue that your customers have mentioned?
No idea what this would have to do with webhooks though. Maybe I've missed the point.