For the raster rendering stuff, check Linus Tech Tips review, the 6900xt only performs like a RTX3060ti.
And if you enable ray traced rendering, the 6900xt like all RDNA 2 cards produces a very noisy image that can't then be used for any commercial purposes - any ray traced rendering looks like it's got the worst film grain known to man.
if you don't like Linus, you can also check out OptimumTech's channel as he also benches rendering because it's something he uses to make his youtube content and he flat out said he would not recommend the 6900xt/6800xt for rendering.