I use phones a lot in Errant. When I imagine how a character would act in any given situation, I often imagine what I'd do and often the answer is "use my smart phone". At first, it was like "Is this going to work, a Fantasy story where everyone has phones?" but then it turns out to be pretty fun, because people tweeting about monsters on their street is inherently funny.
Urien uses his phone as a torch in the prologue, which is the first time we see one being used in the comic.
Subo uses his phone to work out roughly where in the city Rekki is by searching on "sqroller", because she's famous, so of course people are talking about her. I came up with this because when I lived in London and there was a lot of noise outside or something, I'd search my area of London to see if people were talking about a police chase or a riot or something.
Rekki gets messaged by various people who want her to do things throughout the comic (often expressing annoyance or even dread about it), and even writes an apology text when she thinks she's about to die. She finds out about the masked campaigner called Crow because somebody sends a youtube video of one of their rallies.
I often use phones as a way for people to find out about things... but also to get the wrong idea about things. In Shakespeare, people frequently stumble across letters that are misleading in some way, and I think phone messages can be used to the same effect.
Both Rekki and Subo use their phones as alarm clocks (as a lot of people do) and I had fun having the UI and tone of Rekki's be unpleasant and aggressive, while Subo's is friendly and relaxing, to give a sense of the different pace of their mornings.
When Sarin isn't sure what to make of Jules (due to having seen a news video online where their whole demeanor seems villainous!), the first thing she does is what most millennials or zoomers would do: She looks them up online and browses their social media profile and recent posts.
Characters don't need to constantly be taking selfies or instagramming their food. Like my knights aren't always on their phones in the middle of fighting monsters... But if there's a place where it feels like it'd be logical to use your phone, people will.