not sure if this is what you mean but here's what i look out for generally:

• wake-up options. people around my level are usually pretty lazy with their options after they tech, so i usually just look for those and punish them.
• where do they grab? a lot of my gameplan is centered on getting someone to whiff a grab through weird aerial drift and punishing them really hard for it. people also get super tilted for some reason when you keep baiting out their grabs, so that's something i abuse quite a bit.
• what do they do after i hit them? i remember playing the #2 in my region a couple months ago. he faired me, i CCed and rolled, and he read it with a dash attack. it was nuts to me at the time, but it made sense, and i've also started coming up with my own ways to deal with my opponent's defensive choices after i hit them. when i play fox my friends will jump after i nair them sometimes, so if i think they'll jump i'll just jump up with them and uair them for a kill.
• do they have a specific tempo they like to play at? if so, i'll play at that tempo for a while and then i'll be a little preemptive or wait just a bit and hit/dd grab them.
• do they have specific tells for what they're going to do? for example, a lot of the marth mains i've played will walk past my shield and, 90% of the time, they'll fsmash. so i'll just hold shield and punish them for it.