Hi Mark,
Thanks for reaching out. Yes it’s totally possible to add a messenger link to Crio Pro WordPress theme! Better yet you could use a plugin like “Facebook Chat Plugin“, for instance, if you wanted to install the Facebook messenger on your WordPress site.
This is just one example of the many messenger plugins you can add via plugin to your WordPress site. Most major messenger brands should have some sort of representation in the WordPress Repository. It would be up to you to decide which one would function best for whatever you need to accomplish.
I hope this helps. Please reach back out if you have any other questions for us.