i use my Pi-Models 1-3 with CRTs (1x Samsung / 1x Bang&Olufsen)
Of course i wanted to connect the Pi4 also with my CRTs, but i only tried it once and burried that idea.
At least concerning the composite out.
Maybe i had bad luck and my Pi4/the AV-socket is broken, but the picture was H-O-R-R-I-B-L-E!!!

I am still searching for a verfied method to connect with better quality (Gert666, Pi2Scart etc.), but did not find anything that runs out of the box without any issues or performance loss :[