We would love to assist you with setting up Mobile Hotspot on your daughter's iPhone Xs Max. What site does it ask you to go to? If it is the Verizon site, it sounds like we may need to remove the Hotspot Block that may have been set up on her line at some point in time. 

This video https://www.verizonwireless.com/support/how-to-change-features-video/ will show you how to update features on your account. Please let us know if this works for you. 

TamaraH_VZW