How to create a webform In Drupal 8 Using RESTful Web Services ?
Before you create Rest API you must have enable core Web services module list & Install custom "Rest Ui" module and enable it.
Here are the steps to create a webform
Step:1 Go to Admin/Configuration/Web-services/Rest and enable "Webform "
Step:2 select all checkbox and save.
Step: 3 Now you can view webform items