Where can I find the Roll up option?

You can access the Roll up option by going to the Filters > Roll up menu in the Activity section of any module record.
Please follow the below steps to enable Roll up comments in the Contacts module:

1. Log into the CRM.
2. Go to the Contacts module.
3. Select any record and go the Activity section in the Summary View.
4. Click Filters and enable Roll up toggle.