You can create CatalogItem

When a custom flow is defined is possible to make requests to it with the UsingCatalog class

See Service Now Docs to learn more

• You must first create an application in studio inside ServiceNow and then:
  • Create a catalogItem
  • create a flow

var requestCatalog = serviceNow.UsingCatalog<Request>(new Guid("catalogItemIdHere"));

var request = await requestCatalog.Request(new{
    varNameHereString = "string",
    varNameHereNumber = 10,
    varNameHereReference = new Guid(sys_id),
}); ;