According to VG Tech: (in the description)
The versions tested were 1.07 on both Playstation 4 systems and 1.1.267.164 on both Xbox One systems.
- PS4 uses a dynamic resolution with the lowest resolution found being approximately 1792x1008 and the highest resolution found being 1920x1080.
- PS4 Pro uses a dynamic resolution with the lowest resolution found being approximately 2432x1368 and the highest resolution found being 2880x1620, and this is downsampled when outputting at 1080p.
- Xbox One uses a dynamic resolution with the lowest resolution found being 960x1080 and the highest resolution found being 1440x1080.
- Xbox One X uses a dynamic resolution with the lowest resolution found being approximately 3136x1764 and the highest resolution found being 3840x2160.
- All four consoles often render at or near their maximum resolution, but the base PS4 in particular rarely ever deviates from its 1920x1080 peak resolution. Xbox One X does appear to stick closer to its maximum resolution, on average, than PS4 Pro does.
- Edit: A lower count of 2368x1332 was found on the PS4 Pro.
So that's in contrast compared to what DF has found, which said it was fixed resolution on all consoles.
VG Tech (also in the description) releases their stats, and the images they used for pixel counting for anyone to check and analyze.