Is this CLI good to activate in BF? Would it affect the flying styles? Need some advice
set roll_yaw_cam_mix_degrees = 0

it depends... I don't think it's a good setting for people who do a lot of free style acro moves, but those who don't understand how a quad flies and confused about their orientations

I have tried but actually made you hard to judge when is rolling too much or less for yaw spins.. and no way to do invert yaw spins with that too.. so better do it by hands and muscles memory lol

I played with that setting a lot and finally stayed with it.

Its nothing you can configure for testing, fly a battery and judge. One needs weeks of practice to become comfortable with this setting, because you have to reprogram your muscle memory in terms of yaw and roll.

I like my cam at 40° and roll_yaw_cam_mix_degrees at 40, too. The copter is back rolling around the center of the screen, yaw means a clear (visual) movement to right or left. people coming from planes will like that a lot.

One thing to be aware of though, it will make motors work much harder, for example when doing a half roll to inverted hangtime, the constant yaw correction during the roll might reduce upwards momentum a lot.

Personally, when i started flying faster (and therefore needed higher cam angle) i wished to have such a feature just to compensate angle a little bit, but meanwhile i'm glad i never used it - i prefer clean control of all axis, and i find it very satisfying when i manage to do a 'clean roll' manually.