Create an SSO and Identity Store using Cloudformation

Hello.

Although you cannot enable IAM Identity Center with CloudFormation, you can create permission sets, etc.
https://docs.aws.amazon.com/ja_jp/AWSCloudFormation/latest/UserGuide/AWS_SSO.html

Create a permission set with "AWS::SSO::PermissionSet" and link it to the account with "AWS::SSO::Assignment".

PermissionSet:
  Type: AWS::SSO::PermissionSet
  Properties:
    InstanceArn: 'arn:aws:sso:::instance/ssoins-xxxxxxxxxxxxxxxx'
    Name: 'AdministratorAccess'
    ManagedPolicies:
    - 'arn:aws:iam::aws:policy/AdministratorAccess'

Assignment: 
  Type: AWS::SSO::Assignment
  Properties: 
    InstanceArn: 'arn:aws:sso:::instance/ssoins-xxxxxxxxxxxxxxxx'
    PermissionSetArn: !GetAtt PermissionSet.PermissionSetArn
    TargetId: '123456789012'
    TargetType: AWS_ACCOUNT
    PrincipalId: 'f81d4fae-7dec-11d0-a765-00a0c91e6bf6'
    PrincipalType: 'GROUP'