Q&A

Is it possible to customize the badge sizes via CustomUI?

Resizing the whole badge is not supported. The text size below the badge (entity name) is controlled via --ha-label-badge-title-font-size. Changing circle size (but not the text, value, or label) is controlled via --ha-label-badge-size Changing circle size + value + label (but not the text) is controlled via --ha-label-badge-font-size Change the label (only) color via --ha-label-badge-color

All this is unrelated to customUI (unless you want to do this customization per-entity)