CRT dont have a native resolution

Even if a software use a fixed resolution, for example 320x240 you can, deppend hardware , do some tricks too

For example, with winmodelines in 2000+ you can force 320x240 at 120hz and have scanlines, games like Sonic Cd looks way better

CRT of course has no problem displaying any supported resolution - bigger (newer) monitor would support higher resolutions and refresh rates - also depends on the VGA card.

Graphics in games would be much better with higher resolution. But it would require much more powerful CPU. I remember trying The Need For Speed and Screamer. Using VGA 640x480 resolution was a no go on a 486 or low end Pentiums.

In general not, but...

- CRTs have a certain dot pitch (distance between two dots of phosphorus). That puts a practical upper limit on the resolutions a CRT can display without going blurry. In general this will also be around the max resolution the horizontal refresh allows at reasonable vertical refresh, but sometimes the two weren't well balanced and you could set a resolution well above what the tube could properly display.
- a good multisync monitor can display basically any resolution/refresh combination within its specs. But not all were that good, and sometimes certain resolution/refresh combinations resulted in distorted images, or images outside the visible area. Some screens try (and sometimes succeed) to auto-center, you generally have manual controls too, but you might end up having to move them when you change resolutions...
- later CRTs are very, very, sharp and accurate. Combine a Trinitron/Diamondtron aperture grille mask with a late flatscreen CRT tube and you get a display capable of showing high resolutions very clearly. Downside is that low res will look just as blocky as on a TFT. If you want low-res stuff, you're better off with an older mid-range shadow mask display rather than the last generations of CRTs.