This is a topic that varies hugely from league to league. It’s really good to know what the coaches are used to, and also know the “best practice” without going over the top - especially if you aspire to keep going higher.
I always make sure I cover any topics and any Q&A the same with both coaches - to avoid any traps (if a coach asks how to legally take a corner, yep, I will explain to the other coach the same answer. It’s fair and avoids tricks destroying match control in that 1 in a thousand matches!).
I think it’s good to start with the briefest human something: small talk, like good journey, good result last week, something that shows you are engaged and doesn’t need an actual conversation.
Technical things about that match really depend on the league/competition, stadium, any special laws or new guidance.
This season we are now applying the “only the captain can question the ref” guidance. So I mention this to every coach pre-match - in a human way - we are learning this too, we don’t want to give unnecessary cards, the chiefs are trying to clean up the spectacle etc. Basically buttering them up in case of a dissent card later
There are youth leagues I do where the coaches want a longer chat, they want to be asked if anyone has any special equipment to be checked (like a cast), the technical area markings are clear, we have enough mins before the match for line up and photos… they train 5 times a week, there’s a big staff, they have probably travelled with a big group of families, a longer briefing is right for them as it’s part of a special event.