All Framework laptop models have full support for DisplayPort MST (Multi Stream Transport), which allows for a single DisplayPort signal to drive up to 4 displays.
Theoretically DisplayPort MST should just work, regardless of if you are using a DisplayPort Expansion Card with an external MST hub or if you are using a USB-C card with a USB-C hub (which internally requests a DisplayPort signal from the laptop and then has an internal MST hub).
What may vary between models is USB4 multi-DisplayPort as well as DisplayPort bandwidth that is supported.
USB4 has support for carrying a single DisplayPort signal (which can drive multiple monitors using MST), or it can carry multiple distinct DisplayPort signals (which is much less common, except on docks that are marketed for support with MacOS as that doesn’t play nice with MST). Support for multiple distinct DisplayPort signals works fine on Intel based Framework laptops (on both Windows and Linux), however on AMD based Framework Laptops (as well as AMD laptops from other brands) that is spotty (often limited in resolution if it works at all).
I will note that many USB-C hub take valuable bandwidth away from monitors and allocates it to USB 3.0 bandwidth instead, which may limit support for running monitors at full resolution/refresh rate/color depth. Although others limit themselves to USB 2.0 (which still has plenty of bandwidth for peripherals like keyboard/mouse) to maximize quality for the displays.
What I personally would probably do is get this USB-C hub and pair it with a MST hub such as this (I know it says Windows only, but I think they actually mean not MacOS as I see no reason why it wouldn’t support Linux). Disclaimer: I have not tested either of those, but I see no reason why they wouldn’t work.
Plenty of other options exist, however I like that USB-C hub as it allows for full DisplayPort 1.4 HBR3 bandwidth while also having a power port and USB 2.0 ports for keyboard/mouse. That MST hub is one of the few I can find that advertises support for DSC (DSC is a “visually lossless” compression algorithm that can greatly reduce required bandwidth without hurting quality enough for human’s to detect, having DSC is helpful if all three monitors are high resolution/high refresh rate).