To fix this issue No, it wouldn't be possible. You need internet connection to access resources hosted in the Cloud. You would need to store the files locally or on a physical data storage device in order to access them without the connection.
I think the issue was by ths following , A capability of the Google Cloud Platform as it relates to Google Cloud Storage is the functional area known as "Storage Transfer Service". The documentation for this is available here. At the highest level, this capability allows you to define a source of data that is external to Google such as data available as a URL or on AWS S3 storage and then schedule that to be copied to Google Cloud Storage in the background. This function seems to perform the task you want ... the data is copied from an Internet source to GCS directly.
How to read and modify a csv file on one bucket in cloud storage and save the results in another bucket using Cloud Func
around this issue The idea that you’re trying to implement is totally possible and can be achieved using Google Cloud Functions. For that, you would need to create a storage-triggered Cloud Function. More specifically, you can create your function in a way that it will respond to change notifications emerging from your Google Cloud Storage.
Programatically download file from google cloud storage bucket
Does that help I just replicated your use case scenario and I successfully downloaded the file into the temporary folder of a Cloud Function and from there I copied this file into a bucket. In order to achieve this, I downloaded the file using createWriteStream into the /tmp folder since is the only folder where we can store files in a Cloud Function, as stated in the Cloud Functions Execution Environment documentation.