Low-light photography is where the differences show between boys and men, and the Xperia 1 and Galaxy S10+ are both grown ups. Shooting with the primary cameras in the default auto modes, the Xperia takes... the better photos of the two - there, we said it.
It captures fine detail where the Galaxy already smudges things up a bit, has better defined edges in dark areas and little of the halos that the Galaxy renders around bright lights. Add to that the Xperia's slight edge in maintaining color saturation, and there's really little we can say the Galaxy does better. Mind you, the S10+'s low-light shots are still excellent, it's just that the ones out of the Sony are even superior.
Ah, but there's a catch, though. The Galaxy has a Night mode, and the Xperia doesn't. The shots taken that way come with much improved sharpness and an increase in detail, matching or exceeding what the Xperia delivers. There's a significant boost in the dark areas revealing stuff the Sony can't quite see, and the halos around bright lights are a lot better controlled than before, though still there's somehow more of them than on the Xperia. The bump in saturation is also appreciated.
The output from the ultra wide cameras is broadly comparable between the Xperia and the Galaxy's Photo mode, though the Xperia does have an edge in detail where there's light to illuminate it, plus again slightly more saturated colors. Once more, the Galaxy's Night mode improves things considerably, delivering better dynamic range and edge definition for point light sources, but also some more general softness.
In low light, hitting the toggle into telephoto generally doesn't mean the phone will use the actual telephoto camera, instead cropping the center of the frame from the main shooter and upscaling that to the full 12MP resolution. Having said that, the Galaxy's light level threshold appears to be set to a lower level, so its first two samples below are in fact taken with the telephoto module. We're speculating it also has something to do with the illumination in the center of the frame, but we can't be sure. We couldn't get such shots from the Xperia.
So, where the Galaxy does use its telephoto module it captures a better photo than the Xperia with some more detail, though it's inevitably noisier too. When the Galaxy switches to the main cam for telephoto purposes, it largely a coin toss between the two, though we could say we're liking the Xperia's tendency to expose brighter.
Winner: Tie. In low light, the Xperia takes overall superior photos in full auto mode. It doesn't have a night mode though, and the Galaxy does, which helps it produce equally good or better results. If you have several seconds to capture the image, that is.