Just add a few extra mooks, some extra treasure so everyone has a chance to roll around in it. And if a map says one square = five feet, then make it ten.
Generally the biggest issue with larger groups is action economy, so more meat sponges are better than increased level.
Increasing everything by half is the best bet. If a room has four monsters or whatever, add two more.
Sorry I don't have specific builds or more then general guidelines, but I haven't run anything for a larger group since Kingmaker (and that was all ten year olds).