Now this is the kind of silly I go in for.
Voodoo2 is rated at being able to fill 90 Million Pixels per second
RTX3090 is rated at being able to fill 156.2 Billion Pixels per second
So in that one metric ~1735 times as fast.
A more realistic comparison though would involve the much higher resolution, details, effects, and image quality that the RTX3090 can produce. Voodoo 2 at direct X 6/7/8 and capabilities and your RTX3090 happy to do DX9/10/11/12 and all that entails. Not to mention RTX itself. (And both capable of SLI even, might not see that again)
There is likely an artificial Direct3D test you could get both to run. I happen to have a voodoo 2 and a 3080Ti.... tempting, but a lot of work, not sure I have any Win98...