Disabled iPhone Query

My grandmother has Parkinson’s and has disabled her iPhone by mistake. She knows the passcode but the phone will no longer let her enter it. How can I reset the iPhone to allow her to input her passcode WITHOUT PLUGGING IT INTO A PC? Unfortunately she is in lock down due to COVID-19. I tried to reset the phone by removing it from devices under Manage my Apple ID, but the iPhone is still disabled. Any help gratefully received as she’s a bit lost without her phone. Many thanks in advance.