By standard I meant standard size limit, not actual size. I have literally tried dozens of LED bulbs of various sizes on different parts of my car, including some ridiculously large ones, and never had an issue with fitment. Car manufacturers usually design large clearances into their light housings to prevent contact. You don't have to worry about matching halogen bulb sizes, halogens are the most compact bulbs and LEDs usually can't beat their compactness.Unfortunately, either there isn’t a ‘standard’, or most just don’t follow that standard. I’ve not seen many LEDs in a compact size of a standard halogen.
These are the fog light bulbs I used.
The only case you might run into issues is if fitting H11 fog bulbs into H11 headlamp housings due to the presence of a projector lens in the housing.