A Canon Rebel series camera would be a nice start.
I don't recommend the cheapest ones, though. The Rebel T7 and the kit lenses sold with it aren't all that great. The camera is "old tech" in many ways and lacks a lot of features that can be found on slightly more expensive models. For example, the T7 doesn't have a self-cleaning sensor... All the other Canon models do. I used DSLRs back in the day when they didn't have self-cleaning sensors and had to do frequent, manual cleanings. Now using models that are self-cleaning, I only have to do cleanings far less frequently... about 1/12 or even less often. Where I had to do cleanings approx. monthly with the old cameras, now I rarely need to do so more than once a year. Probably even less. I will NEVER buy another digital without a self-cleaning sensor.
The lenses sold "in kit" with the Rebel T7 are also not all that great. It will come with at least the EF-S 18-55mm IS "II" lens. That lens is okay optically, able to make nice photos, but it uses slower/noisier and more erratic "micro motor" focus drive. Usually the other camera models instead come with the better EF-S 18-55mm IS "STM" lens, that has faster, quieter and more consistent "stepper motor" auto focus drive.
The T7 is also often sold in two lens kits. In addition to the 18-55mm, a telephoto zoom is included. This is typically the Canon EF 75-300mm "III" lens.That's one of Canon's cheapest and worst. (Not to be confused with any of the EF
70-300mm lenses, all of which are better!) The EF 75-300mm III also uses slower/noisier micro motor focus drive. In addition, it doesn't have Image Stabilization (IS), which is more valuable on a telephoto lens like this than it is on an 18-55mm (which has it). Perhaps most importantly, the EF 75-300mm III has pretty poor image quality... especially toward the 300mm end of the zoom range.
The EF-S 55-250mm IS STM lens typically offered with many of the slightly more upscale model cameras is a MUCH better lens in virtually every way. It uses a faster/quieter stepper motor to focus. It has IS. And it has much better image quality.
I would recommend at least looking at the Canon Rebel SL2 or SL3. Those are more full-featured cameras, including self-cleaning sensors and a lot more, plus they usually come in kit with a better EF-S 18-55mm IS STM. Unfortunately, most recent SL2 kits I've noticed are including the 75-300 III, which is a shame. I would not buy that two lens kit. I'd buy the EF-S 55-250mm separately instead. The SL3 is being kitted with the better 18-55mm and 55-250mm, so there's no concern there.
The original SL1 was the smallest, lightest DSLR anyone had ever made... but it too lacked a lot of features. It has nearly identical specs to the T6, the predecessor of the T7. When Canon "upgraded" the T6 to the T7, just about the only thing they did was put a new sensor in the camera. Those two are nearly the same other than an increase from 18MP to 24MP in the T7. It was a different story with the SL2, which got a lot of improvements over the SL1. The SL3 has even more (mostly video related).
The next step up from the SL2/SL3 are the Rebel T7i and the EOS 77D. First, note the "i" in T7i. Despite the similarity to T7 (no "i"), the T7i is a MUCH more full featured camera. And don't be fooled because the "Rebel" name doesn't appear on the 77D. It's still a Rebel. It has near identical specs to the T7i, just different control design and an additional display. Plus, the 77D superseded a Rebel model... the T6s. These are more expensive models, the primary difference being a more advanced autofocus system.
The T7 with two lenses is widely available for about $550 (
https://www.bhphotovideo.com/c/product/1485123-REG/canon_2727c021_kit_eos_rebel_t7_dslr.html)
SL2 with 18-55mm STM lens is also $550.
SL3 with both 18-55mm STM and 55-250mm STM is $800.
T7i with those same two lenses is $950.
77D with those same two lenses is $1000.
https://www.bhphotovideo.com/c/compare/Canon_Rebel_SL3_vs_Canon_Rebel_SL2_vs_Canon_77D_vs_Canon_Rebel_T7i/BHitems/1475084-REG_1346763-REG_1329223-REG_1329244-REGBut there's a very good deal on an even better Canon camera right now.... Canon USA website sells refurbished cameras. They are little different from new. In fact, they have the same factory warranty as new. Canon has just announced a new model, the 90D is coming soon. As a result, they are "blowing out" 80D at heavily discounted prices. They are offering the 80D in kit with EF-S 18-55mm STM and EF-S 55-250mm STM lenses for $700! That's about half the usual price for this camera with those lenses. The camera is also a significant step up from all the Rebel series. It has a higher specification shutter, more advanced AF system (similar to, but more features than T7i/77D), uses a larger battery to give more shots per charge, has better sealing for dust and weather resistance and a lot more. Sure, it's $150 more than the mediocre (I'm being nice) T7 and it's not-so-great lenses... but it's a whole lot more camera and much better lenses, for less money than some of the other options.
A 16-year-old might appreciate a mirrorless interchangeable lens camera instead of a DSLR. FYI, the Canon M50 with EF-M 15-45mm STM and EF-M 55-200mm STM lenses is selling refurbished at the Canon USA website for $630. Brand new with the same lenses it's on sale too, for $879 (reg. $1149). The M50 has recently been the best selling mirrorless camera in Japan.
https://shop.usa.canon.com/shop/en/catalog/refurbished-eos-m50-ef-m-15-45mm-f-35-63-55-200mm-f-35-63-is-stm-bundle-black