To make legends look good or fit specific requirements you sometimes have to be creative with the settings for a layer in a legend.
Idea: Add the ability to save the legend-specific settings as part of the .lyrx of a layer.
These could include the patch size & shape, if headings & layer name should be used, font settings, etc.
This will make it much more efficient adding a layer to a map and then adding it to a legend.
Currently you have to manually change all these layer specific settings to a legend when you add the layer to another existing map/layout.