To increase the number of email accounts of a hosting plan, first, you must locate from the "Tree of active services" the service where you want to add it, or you can use the general search engine of the SWPanel to find it:
Once in the Dashboard of the service, you must click on the icon "Adjust the parameters and add-ons of your hosting plan":
You will have to add the number of email accounts you want. Also, you can extend the number of mail Aliases and Distribution Lists that you have in your hosting:
Once added, you must accept and formalize the cost of the service: