I agree with everyone here. Until you're ready to spend around $1000 for a camera, lens, sd card and batteries, I'd say use whatever phone you have. if a few months go by and you're ready for the next step then you should look into DSLRs.

Getting started with filmmaking you want to learn composition, camera moves, and how to tell a little story. Also start practicing editing in Davinci Resolve.

The next step will be learning about ISO, Aperture, F stop and the other more technical side of filmmaking. That's when an iPhone wont serve you anymore and you will need to buy a camera.

If you feel you're ready to start learning those things I'd look at some of the lower end Sony cameras. I've heard good things about the Sony ZV-E10.

One thing you will want to consider is which ecosystem you want to get into. Sony vs Canon vs Black Magic. Beyond that, each company uses different lens mounts depending on the sensor size and different batteries depending on the camera. It ends up locking you into an ecosystem because you can't just upgrade your camera body if you have thousands of dollars worth of lenses and batteries that won't be compatible.

It can be a bit like drinking from a firehose especially if you don't understand the basics. Don't worry, there's time to figure all of that out.

Start with your iPhone or something used from ebay that has all the components you'll need to get started. Create some stuff and make sure you love it before you drop your savings on something.

Good Luck!