Hello, welcome to ERPNext!
The desk customisations are limited in v12. You can show, hide or reorder cards. Check this link for v12 Desk customisations: Desktop
However, you get a lot more flexibility in the desk that comes with v13. You can customise your workspace, add charts and shortcuts for the doctypes you will visit the most and there is a sidebar which will help you switch modules quickly.
Check this thread to know more: Redesigning Desk
Also, the healthcare module has been refactored in v13 and we are constantly adding new functionality. It would be great if you could start using v13 to get the most out of the healthcare module as well as the flexible desk view!