Sounds like Savanna Cats. They are big, and they like to fetch. They can also be walked on a leash.
Mine are leash trained as well. Would love a savanna cat. I truly am a cat whisperer. For some reason they follow me around. When I say NO!!! they stop what they are doing. When I meow at them they meow back. When I purr they also purr. They are sitting about two feet from me. Just purred at them and backatcha boss man. Could be because I cuddled with a lion cub when I was 10 yrs old. (I am from South Africa) https://www.youtube.com/watch?v=1J0C2HlC38c
We are crazy. https://www.youtube.com/watch?v=2f8Hpid8YWA