7 inch display increase character size

Good morning, I connected an IPS Touch Screen with 1024x600 resolution to the Raspberry 4 (with HDMI adapter for the video signal and USB adapter for touch and power).
It all works without changing the config.txt or userconfig file (I don’t know what resolutions it works at, maybe hd?)
The writing on the screen is very small, I would like to use a lower resolution, 1024x600, and I added the configuration lines
hdmi_cvt=1024 600 60 6 0 0 0
but so the display remains black (among other things, I can’t find the meaning of hdmi_mode=87 on the web, the lists consulted go up to 86)
Anyone have suggestions?
Thank you, HI