No, clients cannot see the reports unless you share it with them.
After completing the assessment process, your reports will be automatically generated and you will see a red button providing the option to share a couple-specific report with them. See the screenshot below.
After sharing, your couple will be able to securely access, review, and download their report from within their Gottman Connect account without your needing to email it to them.
If you choose to download the report and make changes, you cannot currently upload the modified report to the Gottman Connect portal. You would have to send it to them by a secure method.