Reddit mentions of OSTENT Real RGB Scart Cable Cord TV AV Lead for Sony PS1 PS2 PS3 Slim PAL Console

As u/Craigerrs said, the SCART spec can vary from TV to TV especially if it's a cheaper one. Short answer for the PS2 is that you want the TV to support RGB over SCART, then you need to get yourself a Playstation RGB SCART Cable
I can't remember offhand, but I think you need to enable RGB output in the Playstation menu.

For other devices; if it is capable of outputting RGB, you'll almost certainly be able to get this into your TV through SCART regardless of the connector on the other end.

Further detail about the connector:
SCART was a very nifty and clever connector for the analogue A/V age; the analogue equivalent of HDMI in many ways. It supported multiple video signal types, multi-channel audio, and comprehensive control signals through a single 21-pin connector and cable.
French invention from late 70s but became widely used throughout Europe and Middle East (basically PAL zones) by late 80s. I'm in UK and it was ubiquitous here in 90s (still offered as a single connector on some flat screen TVs to this day).

The three most commonly supported video signals supported by the SCART connector were composite (OK), S-Video (Better), and RGB (Best). RGB was especially good for anything involving computer graphics (such as games consoles, home computers and on screen graphics from Set Top Boxes). You could connect SCART to SCART, or any supported signal on a different connector wired to a SCART connector at the other end (eg 3xRCA for composite video and stereo audio, plus an S-Video connector at one end, with SCART at the other)

The control elements are largely defunct now unless you are connecting compatible equipment with a SCART connector but they supported input switching (start playing a tape in your VCR, and the TV would switch on from standby and switch to the correct input and back again once you switch the VCR off).
A set top box could send a signal to a VCR to start and stop recording at appropriate times, a VCR or DVD player could set the TV to switch to the appropriate aspect ratio for the content playing, etc.

There were various other functions such as bidirectional signals but one which was useful in reducing cable clutter was the ability to daisy chain devices and pass through signals. For example, you have a TV, VCR, Satellite receiver, and DVD Player. You want to be able to see all of these on the TV, and you want to be able to record programmes from the satellite receiver. Normally that would be a longer cable from every device to the TV, plus a cable from the satellite receiver to the VCR. To further complicate matters, cheaper TVs often only had 2 or even 1 SCART input. One way around this would be to connect the DVD player to the 2nd SCART on the satellite receiver, then connect the 1st Sat SCART to 2nd SCART on the VCR, then the 1st SCART from VCR to TV. One less cable overall, shorter cables in daisy chain rather than rats nest of longer cables, and fewer SCART sockets required on the TV. It might not seem like much but given how chunky good quality SCART cables and connectors could be, the space saving could make a difference.

I'm going to stop now as I'm sure I've bored most people to tears about SCART but it was an incredible connector with a lot of functionality, you could make your own cables to precise length and requirements, and it even supported HD making it more convenient than 5xRCA for Component plus audio but this was very limited as HDMI was on the march.