Thank you for tips! I don’t know where to find a patch that matches the jacket’s leather. What if Put something like an embroidered patch over it? Or better just try and find a similar material to glue it together instead?
Personally I love visible mending such as embroidery, as I think it gives character and history to a well loved garment.
I would suggest putting leather under the tear with glue to strengthen the area, and then do some decorative stitching over it for added security and design!
I’d probably try a heavy cotton underneath as a patch and glue to that. If you could find a decorative braid or something that looks ok in a complimentary colour you could glue that around the cuff where it has torn for further reinforcement.
Possibly a strip of perforated leather or vinyl would work.
That gash makes me curious what happened?
I would probably either remove the entire cuff (as it looks sewn on to the rest?) and replace it with something else - fabric (denim?) or leather if you can get hold of some. Or I would add something to the back - fabric in a similar colour - and use leatherwork needles to sew the gash shut with x-stitching. That way you close the gap, keep the leather look and get a "feature" from the stitch.
I have patches on my leather jacket that is the same colour as yours. I think they look cool but they're smaller and in a less annoying place (I worry a might make the cuff too thick in that spot). My preference for your jacket would be obvious stitching in a noticeable colour, but that's just me.