Hello, @IP,
That is because in this Demo https://xstore.8theme.com/elementor/demos/car-parts/product/sinister-diesel-series-30-power-hydraulics-turbo/ there is no sidebar set, but all the content is in Single Product Builder.
And in this demo: https://xstore.8theme.com/elementor/demos/niche-market02/product/wooden-classical-golden-chairs/ we have the sidebar set.
So if you want the content or tabs section full width, you have to remove that sidebar and choose the Layout as without the sidebar from XStore >> Theme Settings >> WooCommerce >> Single Product Builder >> Layout: https://postimg.cc/Vdft4HPC
Regards 8Themes Team.
