Shopify's default free theme (v11.0.0 – v15.5.0). Go to Styles & Settings → General Settings → Display to enter these settings.
Settings
Inject: Before
Selector type: CSS selector
Selector: .quantity__label
Kiwi Injection Guide - Dawn - Above Quantity Selector
Injection settings for the Dawn theme to place the Kiwi size chart above the quantity selector. Go to Styles & Settings → General Settings → Display.