In the below snippet, can I do a lookup for the IGW using a function (or something) based on the VpcId parameter instead of needing it as a parameter?
Parameters:
  VpcId:
    Type: AWS::EC2::VPC::Id
    Description: Enter the Existing Landing Zone VPC ID. 
  InternetGateway:
    Type: String
    Description: Enter the Existing Landing Zone IGW.
Resources:
  DefaultRoute:
    Type: AWS::EC2::Route
    Properties: 
      DestinationCidrBlock: 0.0.0.0/0
      GatewayId: !Ref InternetGateway
      RouteTableId: !Ref RouteTable
Thanks.
I have not tried anything because I can't find anything that makes me thinks this would work, just not sure if I am missing something.