Of the lists available in the Apps section on Portal, apps in the Favorite Apps list can be arranged in your order of preference.
For details on the steps, refer to Reordering Favorite Apps.

You cannot reorder apps in the lists except the Favorite Apps list.
For your reference, here are some workarounds you can use to organize apps or facilitate access to certain apps.

• Establish an app naming convention and use the "All Apps" list
  The All Apps list displays apps in name order.
  Establishing an app naming convention (e.g., adding sequential numbers or common characters to the beginning of the app name) beforehand helps you keep the apps in the All Apps list organized.
  
  

• Use the "Announcement" section of Portal and spaces to facilitate access to frequently used apps
  Administrators can take the following actions to make it easier for users to access frequently used apps.

  • Attaching apps to the "Announcement" section of Portal or spaces
    Is it possible to arrange apps on Portal in my order of preference?
  • Inserting bookmarks for apps into the "Announcement" section of Portal or spaces
    Create quick links to frequently used apps