You can't add RAM via an external GPU enclosure.

No. It doesn’t work like that.

An external GPU enclosure connects over Thunderbolt or USB4 and uses its own video memory (VRAM) for graphics tasks. That VRAM is not system RAM. The laptop’s CPU and operating system can’t use it to run applications or store data the way they use soldered RAM. They’re completely separate pools.

Even if you had some fancy PCIe expansion chassis that exposed memory to the system (which basically doesn’t exist for consumers), the latency would be terrible and the laptop’s BIOS/EFI would need to support it. Most soldered-RAM laptops have no such option.

If you need more RAM, buy a laptop with upgradeable slots or get the max soldered configuration up front. External GPU enclosures fix graphics, not memory.