Question about Corsair K55

Theoretically, there is no such thing as a "fitting" mouse. A suitable mouse only exists if you like it and it fits your hand well. I'm guessing that you would prefer a mouse that fits for gaming. If not, I recommend this Logitech MX Master 3 (Wireless) . If so, I recommend an inexpensive one: Glorious PC Gaming Race Model O (Wired).
A medium expensive one: Razer Viper (Cable)
An expensive one: Logitech G PRO Wireless Gaming Mouse (Wireless)
And a very expensive one: Razer Viper Ultimate (Cable, Wireless)