iOS 14 UISplitViewController Triple-Column Layout in Interface Builder, show only Two Columns in Landscape on iPhone?

Previously you could set the width of the preferredSupplementaryColumnWidth to automaticSupplementaryFillDimension, but this API seems to have been removed.

hideColumn: method seems to have no effect.

Any one manage to show only Two Columns in Landscape on iPhone using UISplitViewController with a triple-column IB setup? Triple column layout is utilized on the iPad/Mac, but want two columns, max, on iPhone in landscape.