InitiateAuth command to Cognito User Pools in custom query

I try to setup my custom connection without any SDK in Salesforce Apex to control a User Pool. The first I try to setup a POST query with InitiateAuth command. It looks like:

curl --location 'https://cognito-idp.us-east-1.amazonaws.com'
--header 'X-Amz-Target: AWSCognitoIdentityProviderService.InitiateAuth'
--header 'Content-Type: application/x-amz-json-1.1'
--data-raw '{ "AuthFlow": "USER_PASSWORD_AUTH", "ClientId": "tests11hrd1ejlahf48t", "AuthParameters": { "USERNAME": "user@share.com", "PASSWORD": "pass" } }'

The answer: __type": "ResourceNotFoundException", "message": "User pool client testejlahf48t does not exist."

Please, anybody tell me how to setup custom connection InitiateAuth?