Larger seems ill advised. Frankly anything that wasn’t meant to be used in that way seems ill advised since the cord may not have the proper strain relief and be intended to be used to remove the toy from an orifice.

But going larger definitely feels like it creates more risk of putting too much strain on that cord, breaking the connection at one end, and leaving the toy stuck

Thats my two cents, but I’ve not used that particular type of toy so hopefully someone with more knowledge can chime in.