The SL3 is also Canon's first Rebel camera with 4K. Unfortunately, however, it doesn't work with Dual Pixel, significantly crippling its autofocus capabilities (you're limited to contrast-detect AF instead). On top of that, the sensor is cropped by 1.6 times, like it is on the EOS M50, giving you an effective sensor size that's smaller than Micro Four Thirds. It also lacks sensor-based in-body stabilization, using digital IS instead that also introduces cropping.
As for other specs, you can shoot at 5 fps, the ISO ranges up to 25,600 (51,200 expanded) and the battery delivers a whopping 1,600 shots, or 350 with live view, much like the last Rebel SL2 model. Other new features include an automatic "smooth skin" mode that should go well with the flip-around selfie screen and a feature assistant guide that lets you blur the background -- like a smartphone -- even without a fast lens.
The Canon EOS Rebel SL3 arrives at the end of April for $600, or $750 with an EF-S 18-55 mm f/4-5.6 IS lens. At that price, its closest rival is probably Nikon's $500 D3500 DSLR, and despite the 4K limitations, the SL3 looks like a much better camera for just $100 more.