That too. Especially in open-world games, distant objects are loaded with less details and everything has lower resolution textures. The lower detail of distance objects increases rendering performance, and the lower resolution textures take up less memory.
Decreasing the resolution of textures only decreases the memory requirements if no object close to the player needs a higher resolution version of the same texture though, since then you even need to keep 2 instances of the same texture in memory.
Decreasing the resolution of textures only decreases the memory requirements if no object close to the player needs a higher resolution version of the same texture though, since then you even need to keep 2 instances of the same texture in memory.