That would depend on the FOV Type of the game. If the game is not using an FOV Type related to the entire horizontal axis (Horizontal Degrees (Resolution Base) or Horizontal Radians (Resolution Base)), the game will account for the horizontal resolution by increasing the horizontal FOV. So those games that have horizontal FOV Types locked to 4:3 or 16:9 will be unaffected by horizontal resolution as well as those that use vertical FOV.
Here's a few examples:
CSGO 16:9 will have the same pixelratio as 43:18: https://www.mouse-sensitivity.com/?share=acab8d2e68bd44f16017e014e5d13e79
Because the horizontal FOV increases with the resolution change.
Overwatch 16:9 will have a different pixelratio than 43:18: https://www.mouse-sensitivity.com/?share=5b0b79d8a0cd3cf4e65b0191d30491e1
Because the horizontal FOV stays the same.