If you have a camera with manual settings, you can control its aperture using Aperture Priority (Av) mode. The aperture setting simply tells your camera how much light to allow in. In low-light conditions, you need to let in as much light as possible to get a good exposure and capture the detail in the scene. To do this, use a wide aperture (low f-number). If your shot is still underexposed (too dark), using a slower shutter speed will also let in more light by increasing the exposure time, but at the risk of blurring – see the section below on keeping your images sharp.
The aperture setting affects more than just the exposure, though. A wide aperture also results in a shallow depth of field – that is, at a low f-number, only a narrow slice of the scene will be in sharp focus. This might be ideal if you're shooting pre-dawn portraits and want a pleasingly-blurred background, but if you want to capture the special nuances of a cityscape at dusk, for example, then using a narrower aperture (higher f-number) would produce greater depth of field, so that more of the scene will be in focus. For a good exposure, you would then need to try using a slower shutter speed.
Naturally, some lenses have a wider or 'faster' aperture than others. Excellent compact options for EOS R System full-frame mirrorless cameras such as the Canon EOS R6 and EOS RP include the Canon RF 35mm F1.8 MACRO IS STM, a great pick for wide-angle shots of night-time cityscapes and other low-light scenes. The Canon RF 50mm F1.8 STM gives a more standard perspective (similar to the human eye) and is ideal for candid street photography scenes shot at night, while the longer telephoto reach of the Canon RF 85mm F2 MACRO IS STM makes it superb for low-light portraiture.
If you're using a DSLR, a lens such as the Canon EF 35mm f/2 IS USM offers a natural perspective and the benefit of image stabilisation (IS) for handheld shooting. The Canon EF 35mm f/1.4L II USM, with its even wider maximum aperture, has exceptional low-light capabilities. If you have a DSLR camera with an APS-C format sensor, such as the Canon EOS 850D, then an EF-S lens such as the Canon EF-S 35mm f/2.8 Macro IS STM would be a good option for a natural perspective. If you're after similar wide-angle and natural perspective for an EOS M mirrorless camera such as the EOS M50 Mark II, which also has an APS-C sensor, look no further than the ultra-compact Canon EF-M 22mm f/2 STM pancake lens and the super-fast Canon EF-M 32mm f/1.4 STM.