Canon cameras including the EOS 90D, EOS 7D Mark II, EOS 6D Mark II, EOS 5D Mark IV and EOS RP have a dedicated multiple exposure function in their Shooting menu. Professional cameras such as the Canon EOS R5, EOS R6 and EOS-1D X Mark III offer additional settings. This feature is available whether you're shooting RAW or JPEG images. Within the multiple exposure shooting options, there are two methods of shooting: Function Control and Continuous Shooting. There are also several exposure settings (although not all cameras have all these options) that can be adjusted to tailor the final output to suit your needs: Additive, Average, (Comparative) Bright and (Comparative) Dark.
Bear in mind that even if your camera doesn't feature multiple exposure shooting, you can still combine images with the Compositing tool in Canon's Digital Photo Professional (DPP) software. DPP gives you even more creative options, such as adjusting the visibility and position of each image within the composite image, and selecting from a number of blending modes.