To create a Date Only package in your Package Manager:
Start by navigating to the package manager by clicking on Manage --> Packages. From there, decide which Service and Package Group you want the package to be in, then:
Click Add a Package.
Enter the title and description of the package.
Click the Pricing & Scheduling tab.
Select Date Only and enter the number of days you want the package to include.
Click Save.
To allow the client to add extra days, change the setting to Yes in the Pricing section: