How to Add Subcollections in Shopify Symmetry Theme

Symmetry has a real native subcollections feature — a way to divide one large collection into smaller, linked groupings, rather than the manual "Collection list" workaround free themes need.

Steps

In your Shopify admin, go to Online Store > Themes and click Customize on Symmetry.
Switch to a Collection template using the page picker.
Select the subcollections section or block.
Choose which collections to feature as subcollections of the one you're viewing — Symmetry may pull suggestions from your navigation structure or let you pick manually.
Click Save.

This is a genuine advantage over Shopify's free themes, which have no true parent/child collection relationship — a Dawn-based store needs a manually placed Collection list section instead, which only works as a static block, not live navigation on every collection page.