In applications using Universal Theme 21.x, item- and region-level Stretch Form Item/Fields template options on Display Only page items with the Optional/Required or Optional/Required - Above item templates are ignored:
Demo
As a result of the items not being stretched to fit the allocated column span, the u-textStart/Center/End UT modifier classes do not work as required.
As shown this has changed from previous releases and is inconsistent with the behaviour of the corresponding Text items and Display Only items with the Floating item templates, which do exhibit the expected layout and formatting.