Push text files between my phone and my laptop using native OS/apps, not third party installs?
AirDrop:

With AirDrop, you can wirelessly send documents, photos, videos,
websites, map locations, and more to a nearby Mac, iPhone, iPad, or
iPod touch.

You should be able to “share” the text file and select your iPhone under AirDrop.

Another option is to Copy and paste between devices:

With Universal Clipboard, you can copy text, images, photos, and
videos on one Apple device and then paste the content on another Apple
device. For example, you can copy a recipe from your Mac and paste it
into a note on your nearby iPhone.