Is there a way to tag someone based on what link they click on in an email and/or post in Series?

Hello @jolie​ , Hope you are doing well.

As far as I know there no such feature to do this. 

If these links are on your web-site (Where Intercom installed), You can use Series and UTM to tag them.

1. Use UTM tags before send the link.

Example: https://webiste.com/?utm_source=Intercomamp;utm_campaign=onboarding

2. Start Building Intercom Series:

Entry rule:

Then tag users once they match the entry rule:

I tested and it's working fine. Just let me know if you have questions.