When I choose one entity and one of records, the tags change as following pic. Can they be designed?
changed:
What does the icon means?
They are not Tags, they are ribbon buttons/commands. You have to use CRM Ribbon workbench (Managed solution or XrmToolBox) to customize the ribbon/command bar. Read more
The ribbon/command bar button can have display rule/enable rule, based on that rules they will show hide. For ex. If “selected record count rule” triggers then the options are different in view.
To update the icons, you have to upload svg icon in each custom entity. And make sure to update the modern image in ribbon button definition.