How to make lists full width section in sharepoint?

If you mean a list embedded in a modern SharePoint page, the standard List web part does not support full-width sections. Communication sites offer full-width sections, but only compatible web parts can be placed there.

To give the list more room:

1. Edit the page and select the section containing the list.
2. Change the section layout to One column.
3. Move any web parts beside the list into another section, then republish the page.

This uses the normal page content width, but some outer margins will remain. A one-column section is not the same as a full-width section.

For more working space, click See all on the List web part, if shown, or open the list directly through Site contents. That opens the full list interface instead of the embedded view.

If you are already viewing the list directly, page section settings will not affect it. You can adjust column widths and remove unnecessary columns from the view, but JSON column formatting cannot remove the surrounding page margins.