Usually a combination of search, time-based ordering (like: "I did this thing a while ago, let me scroll back 1000 items") and some mental landmarking (tracking some stand-outs in a list to know the relative position of other items). Same thing with pictures/photos, you could have them in albums, or even smart albums with tags etc, but people tend to just have a running list of all pictures in chronological order.
Most systems have or used to have tagging functionality as well, but apparently that wasn't used all that much either for information classification and organisation.
Granted, I can't read minds and I don't know what everyone everywhere does, but I do see large scale changes in employee instructions for new hires, university hires and even in cross-org/education projects. For most young/new people, their phone was their first 'computer' and the 'default' environment, and a desktop is the anomaly. People looking up how to do things on ticktock is not a funny meme, it's reality and seriously tainting the knowledge of junior hires on the lower end jobs (like entry level service desk backoffice). Knowing where to find authoritative information, how to verify it, and how to use that as a reference to validate and find other information seems to be a foreign concept to some as well. Even something like a somewhat specific google search or wikipedia article and the references it can supply are not as normal as one might think, and the gap is getting bigger, not smaller.