I've been working on a portable raspberry pi zero w for a while now and I've soldered the yellow and white wires from a 480x240 tft LCD display directly to the pis two tv pins. It may be hard to tell from the photo but the image on the screen is pretty fuzzy making it impossible to read small text. I'm not sure what the problem is but I'm really new to this stuff so I did a pretty shotty soldering job if that makes a difference
Composite video only has a bandwidth of about 5MHz. That means, if you had e.g. 30 frames per second, you can only display about 166.000 pixels per frame, minus overscan and sync. All above gets blurred down to this.
EDIT: Unfortunately, you cannot change the composite resolution on the Raspberries, it's fixed to 720x480@60i for NTSC and 720x576@50i for PAL. For a CRT – TVs are meant to be a bit blurry – it makes no difference but it doesn't match TFTs as your display well.