To automate this, I suggest you following these steps.

1. Check the Slack bolt Api and create a bot which would listen to certain triggers such as slash commands. (Example: typing /create-sheet would trigger a UI element on slack which would be a form with necessary fields to add a google sheet)

2. Use N8N. Create a workflow (Webhook -> google sheets create node). When you submit the form through slack. You trigger a webhook with necessary data to create a google sheet. Rest would be handled by n8n.

Please check Creating a slack bot Please check n8n google sheets automation.