You don’t need a webhook trigger to transfer/move already existing data. You can either use a Search module, or export your notion database into a format (like CSV, XLSX, etc.) that can be uploaded and converted into a Google Sheet.
If you need more help with your scenario, perhaps exporting the blueprint might help others replicate the issue to be able to answer your question.
At the bottom of the scenario editor, you can click on the three dots to find the Export Blueprint menu item.