ImageRenderer

Image -- the picture at a URL, drawn by the host's loader.

variant chooses the size and fit the scaling, both as the implementation guide lays them out. The variants that name a fixed square get one; the two that the guide calls full-width -- largeFeature and header -- fill the width they are offered, and mediumFeature, the default, fills its container but stops at 300dp.

That 300dp cap is doing more than following the guide. A fillMaxWidth taken inside a Row resolves against the width the grandparent offered rather than this image's share of the row, so an uncapped image beside anything else takes the whole row and leaves its siblings at zero -- the failure TextField carries a note about. A bounded widthIn cannot do that, which is why the default variant has one and the two banner variants, which the guide means to sit alone at the top of a surface, do not.