The Shopify theme “Dawn” allows you to choose either one or two columns to display on the mobile screen by default, but with a little tweaking, you can also display three columns.
How to make the number of columns in the featured collection section and collection template of the theme "Dawn" compatible with three columns on mobile

[Settings Step 1: Product Grid Section] Add the scheme to "main-collection-product-grid.liquid" and the label to "ja.schema.json"

[Settings Step 2: Featured Collection Section] Add the scheme to "featured-collection.liquid" and the label to "ja.schema.json"

[Settings Step 3] Modify base.css

