Photography

I'm a week late and others have already given you some good answers, so here are some quick thoughts.

• compact has two components: the body itself and the lens
• smaller sensors usually result in smaller bodies, but some modern micro four thirds cameras cameras use full frame bodies (looking at you Panasonic) and some full frame bodies like Sony's A7c are very compact
• Lenses designed for smaller sensors will be more compact for an equivalent focal length, but you'll only maximize the size benefits if you get a lens designed for the sensor. For example, you can put full frame glass on an APS-C sensor and it will fully function but if you can find an APS-C native lens it will be smaller. This is actually a strike against Canon, Nikon, and, to a lesser extent, Sony as their current mounts are biased towards full frame glass
• Low light has two main components: how slow you can let your shutter go and your lens aperture. If your subject is still you need not worry much about low light assuming you can keep the camera steady via stabilization hand holding or a tripod/monopor. If your subject is moving you'll need to gather light more quickly. There are two ways to gather light more quickly: more sensor surface area and a wider aperture lens. A full frame sensor generally gives you a two stop advantage in terms of noise, so say a f/1.4 lens on a micro four thirds camera would yield similar results as a f/2.8 lens on a full frame body
• If you consider the prior bullet you can actually make a pretty compact full frame setup. An A7c with sonys 50mm f/2.5 lens is nearly as small as a GM5 with Panasonic's 25mm f/1.4 lens and the two will achieve pretty similar low light performance. This won't hold up if you want more reach though. I'm lugging an A9ii around with Tamron's 150-500 and it's way bigger than my old D5300 + 70-300 despite similar equivalent focal lengths
• Some of the most compact cameras are out of production. The greatest camra ever made is a GM5 and it fits your form factor well. The smallest interchangeable lens camera I've personally owned was a Nikon J5
• Older cameras absolutely still take great photos but tend to give up video capability

I was happy with the performance of my D5200 so it's a good benchmark and should be easy to beat i think

The amount of ISO you can get out of somewhat newer/higher tier sensors is great. A fast lens on your D5200 would probably help a ton with low light, but being able to push 12,800 ISO combined with a fast lens means that I don't own a flash for my current body. As a bonus, mirrorless lenses are generally more compact than their DSLR counterparts

For the trip we currently just have our phones which are an iPhone 16 Pro and a Google Pixel 5a 5G that both take pretty decent casual photos. The camera I'm looking for doesn’t need to replace that, but needs to offer significantly better image and video quality.

Cellphones take totally serviceable photos and video given adequate lighting, slow subjects, and "normal-range" focal lengths. I still use a dedicated camera because I have kids that...

• like lower light situation, especially during the winter. Think museums and other indoor attractions, the holiday displays at the local zoo, etc
• play sports. You need both good autofocus and reach for this. I've been defacto team photographer for four seasons now

I also find that a dedicated camera puts me in a more creative mood.