During the Geforce 2, 3 and 4 era these were known as "VIVO" models, but some also just had plain TV out also. Often this was through one of those 4 pin Din style SVHS video connectors, where you'd use an adapter cable (common) to connect to RCA jack composite in. Or some TVs would take the SVHS cable. Rage II/Pro/128 also had TV out as a common feature. Certain Voodoo 3 Models, I think 3000 had it. After Geforce 4 series and Radeon 9x00 series cards it seemed to die off a bit, though there were some models had it still.

edit: Oh by the way, often this needed to be setup in windows, not sure of a solution where you can just plug it into composite and go. Usually they worked in clone main screen output mode. I think you can set it up once with a VGA and then you can boot to composite out, but you won't see BIOS screen etc usually until it's into windows. There are such things as VGA to composite converters that convert whatever it's putting out at whatever time to some kind of composite signal.

Voodoo3 definitely can be used VGA-less. 😀

I would just convert the VGA output using a cheap device .

Native RCA composite at boot was rather rare, not even sure a custom video rom exists to do it.

The output quality is going to be horrid either way.

What is the reason you want composite out... other than playing on an old TV?