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I really don’t think it’s an issue. Any 24-105 for FF will be this sort of size - compare it with other lenses from Sony, Canon etc. It’s also not a lot bigger than the Olympus 12-100 for m43, but of course that lens has a bigger range.
But if you want smaller, the Sigma 28-70/2.8 is an option, but it has a much smaller range and no OIS.