You can resize selected model items so that they match.
Prerequisite
For this model, the Resize symbol option for text attributes in the symbol was not selected in ARIS Architect (Model properties > Format > Representation > Text attributes in symbols).
Procedure (quick video)
The selected model items are resized accordingly. To avoid destroying the general model layout item placement is not changed. This means the center point of the model items remains where it is. Align the changed model items again if the size change results in an irregular placement of the items among each other.