To control the content width and corner radius for your store go to theme settings and click on layout & styling options:
Content Maximum Width
Set the maximum width for your content.
This setting determines the maximum width of your content area. By default, it is set to 1600px, but you can choose to make it full width by selecting 2000px.
1600px: The content width will be limited to 1600 pixels.
2000px: The content will extend to the full width of the screen.
Choose the option that best suits your design preferences.
Corner Radius
Customize the corners of styled elements.
With this option, you can choose to round the corners of various styled elements on your store, including checkboxes, selectors, boxes, labels, and the search bar.
Show All Elements with Round Corners: Enabling this option will apply rounded corners to all these elements, giving your website a softer and more visually appealing look.
Customizing corner radius can help you achieve a specific aesthetic for your website, so feel free to experiment and choose what fits your design style best.