Can be anything, iOS shortcuts, Tasker, bash scripting, home assistant/homebridge, etc.
My old house I had a pretty nice Home Assistant setup, I still need to move everything over to my new house and set it up. Things like automating lights, laundry machine speaker and phone notifications, TV notifications and reminders, dehumidifier triggering, climate control.
I also have some simple automations going on my linux server for maintenance and backups. I run Plex_Debrid on my server and sometimes the Real Debrid docker volume goes out. So I have script running every few hours to run a docker exec command to see if any files are showing in the realdebrid directory and if not, take down the plex and plex_Debrid docker container and re-map the volume and boot back up.
iOS shortcuts is pretty handy, for some reason the light/dark mode transition on my iPhone doesn't work great so I made a shortcut automation and it works much better. I setup a pretty cool NFC Medicine Taking system as I have to taken a few different meds every day and at different times. I can just tap my phone on my medicine and it will tell me if i have taken it yet or if its time to take it. Very helpful with my ADHD causing me to forget to take them all the time.
I know I have more I am not mentioning now, plus a whole assortment of different automations to automate my job.