The novelization states that Golden Frieza's power is enough to at least shake and damage SSJ Broly somewhat if any of Golden Frieza's attacks actually connected and SSJ Broly was implied to be the strongest mortal he ever encountered by Frieza. If Frieza's attacks can actually faze SSJ Broly without having to catch Broly by surprise, it's safe to say that his power should be greater than anything SSJ2 Kefla could accomplish.
And to piggyback off of what
@GreatSaiyaman123 already mentioned, Golden Frieza is definitely stronger than the combined assaults Blue Goku and Blue Vegeta initiated on Broly given the implications of the Broly novel. With Blue Goku and Blue Vegeta's powers forcing Jiren back (who was stated to be the strongest power ever encountered as per Ep. 122) and causing him to enter a Powered Up state, Golden Frieza should be stronger than SSJ2 Kefla.
That also seems pretty consistent with the manga. SSJ Kefla is slightly above Blue Goku presumably, Goku powers up after the Tournament of Power by training, but Golden Frieza evidently pulls way ahead.