It will really depend upon how dim the scenes are that you're trying to capture. Capturing such images can be very challenging and often push your gear to their limits.
A Rebel T7 won't have very good ISO performance, so you'd really need to pair it with lenses with wide apertures (e.g. f/1.8). A typical kit lens that comes with the T7 would have variable apertures with the widest being around f/3.5, so would let in half the light as compared to f/1.8 (or less when zoomed to longer focal lengths).
You'd be better off with a newer R-series camera as it would have better ISO performance (e.g. look at the EOS R10. Or R50 or even R100 if you don't have much budget). Though a good lens will also be extremely useful. There are very good zoom lenses with constant f/2.8 aperture (e.g. RF 24-70mm f/2.8 or RF 70-200mm f/2.8). Those zooms are quite expensive though.
Personally, I much prefer prime lenses for low light work as they can have very wide apertures (down to f/1.2). Though primes and working with such wide aperatures also come with their own cons.
I believe all of Ricky's recommendations are good ones. Anything DSLR is being discontinued or is on the decline. An R series body is the direction you want to go in from a performance and investment standpoint.
I might advise differently if you had a stable of lenses, but there are more reasons not to invest in DSLR and EF lenses than Mirrorless and RF. It's also possible to adapt EF glass to mirrorless bodys but not vice versa. So in this case an older body would be your limiting factor, and not as wise an investment in the long run.
Photography is not an inexpensive hobby. As time passes. The majority of your expense will be in lenses, not in the camera body you choose. Think about the type of pictures, and the shooting environment you intend to use the camera in primarily. What have your biggest challenges been? For the type of performance you are describing, a body with interchangeable lenses is needed. You need to be okay with this. No one is saying you need to walk around with a lens in every pocket, but having one or two really good lenses can make all the difference. After you decide what's important to you, photos, video, both and what type of photography is important... Landscapes, architecture, wildlife, etc we can help guide you a bit more. Of course, you do have to identify a budget also.
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