Create a dynamic data that changes on emails?

Hi, I am doing a webinar every 1-2 months.

I have about 3-5 emails sent for each one, and I noticed that I get confused with changing the dates or links sometimes.

Is there an easy way to set global variables somewhere that I can change from one page and they will update all emails?

At the moment, I use Twig templates and create different templates for each element: date, time, hour, link, calendar link.

It seems a bit messy to edit 5 templates each time; is there an easier way to do it where I can edit all data from one place and it updates the emails?