Hey OP! At first I was going to recommend you the iPhone SE 2022, the one with an A15 SoC and 4GB of RAM. It is really compact, the most lightweight iPhone currently on the lineup, very robust (I have dropped it innumerable times and still behaves like the first day) and does perfectly what you ask for. Also you can find it at a quite cheap price point.
But then, I read that what you value the most is battery life, battery time. If you don’t use social media apps, don’t play games on it, and don’t watch movies/series on the phone, then the battery life can be decent on iOS 18.1.
However, the newer, bigger iPhones offer bigger batteries and, in theory, more efficient chips like the A18, so with a minimalistic use, you should get more hours out of it. But my iPhone SE3 (2022) lasts all day without issue, and gives me circa 8h of screen on time, with low screen brightness and WiFi. And between 6 & 7 hours with more normal use combining WiFi and data being outdoors.
I would personally give it a try, especially if you find a good deal, if the small screen (by today’s standards) and being three generations older don’t put you off.
Otherwise, I’d wait for the iPhone SE4, which is likely coming next spring with a bigger size and bigger screen, using the iPhone 14 body and form factor, and will probably be powered by the A18 SoC and 8GB of RAM just like the iPhone 16, at half the price.
EDIT: Woops, looks like OP got their account cancelled. Is this usually done by moderation, or the user closing their account? Anyways, for anyone looking for a minimalistic iPhone, my advice still stands as of December 2024.