Question about Samsung C49RG94SSU

Hi, your laptop according to specifications should support two 4K monitors with up to 4096x2304 resolution each, which makes almost 19M pixels altogether. One C49RG90 has 5120x1440, having two means feeding about 14.7M pixels. So in terms of support you should be fine.
Nevertheless (and I speak as owner of two C49s) I don't know your use case, but consider the significant curvature of the display. If you place them next to each other, you will find yourself almost in the middle of semicircle made of displays with diameter of 2,5m :)
On top of each other, doable, sure, but you're looking at ~120cm wide and 68cm high construction, I personally would not appreciate looking at this TV sized setup from 1 meter.

Hi it all depends on what your doing with the mac a mac air isn't designed to do anything to heavy but it should be OK for Web and work