Have you tried doing:

from google.cloud.scheduler_v1.types import HttpTarget as Target


from google.cloud import scheduler_v1

project_id = XXXX
client = scheduler_v1.CloudSchedulerClient.from_service_account_json(
    r"./xxxx.json")

parent= client.location_path(project_id,'us-central1')
job={"name":"traing_for_model",
     "description":"this is for testing training model",
     "http_target": Target(uri: "https://us-central1-gerald-automl-test.cloudfunctions.net/automl-trainmodel-1-test-for-cron-job"),
     "schedule":"1 0 * * *",
     "time_zone":"utc+8",
     }
training_job= client.create_job(parent,job)

I haven't tested this code, but it's clear that you're sending the string to the http_target, and the instance of it needs to be an actual HttpTarget object, and not just a string.

Yes, you will need App Engine and the Cron service to schedule those scripts. You have some more or less straight-forward options to run those scripts on GCP:

• Deploy each one as different functions, and do something as mentioned in here: Basically deploy a simple function in App Engine that sends an HTTP request to your(s) function(s).
• Deploy each one as different handlers in App Engine, and schedule each calls.
• Deploy each one as different services and then schedule the calls, bearing in mind that, if you want to schedule a call to a different service, you must specify to which one, in your cron.yaml file, using the target keyword and the name of the service.