“Glows cannot be seen through transparent objects, nor in reflections. The glow you specify here does not act as a light; other parts of the scene will not be lit by the glow, nor will any shadows be cast. Glows are restricted to a maximum image resolution of 4,000 x 4,000 pixels. When using object motion blur, glow applied to lights may cause colors to overlap.”
If you have AR you can use the glow there which does not have a size limitation (or it’s bigger than I’ve tried).