iPhone Mobile hotspot won’t work. Can’t find a solution online.

Looks like it's on Verizon's end. And that your plan might not come with hotspot option.

Go to your Verizon account via Safari and see if you can activate the option from there.

https://www.verizonwireless.com/support/mobile-hotspot-faqs/

 

https://www.verizonwireless.com/support/knowledge-base-41004/

It may have been a glitch but when you tap on that it should've taken you directly to Verizon website to sign into your account to make the changes to enable Hotspot. Your current plan may not have hotspot enable and you may need to do an add-on.

 

Looks like the Verizon app you are using is out of date, per the video.