I'm using a Pi 3B+ with the composite output cable. I had to set
[pi3]
temp_soft_limit=70
dtoverlay=vc4-kms-v3d,composite=1
include crt/recalbox-crt-config.txt
in config.txt in order to be able to get a picture on bootup.
This dtoverlay line containing "composite=1" is not mentioned in the article on CRT at https://wiki.recalbox.com/en/tutorials/video/crt/crt-screen-with-composite , but probably should be.
Unfortunately, there is massive overscan, not sure how many pixels, but it seems huge. overscan is supposedly disabled by default.
I tried to play with the settings mentioned at https://wiki.recalbox.com/en/tutorials/video/display-configuration/image-size-settings-overscan-tft but they unfortunately did not improve things.
Does anyone have a suggestion ? I would rather have black bars on the sides than have the picture seemingly cropped.