How i can add a "Breathing Effect" in unreal engine 4 player?

I made a fps controller from scratch and i would like to add a breathing effect like the one in “Bendy and the ink machine”

Looks like a very subtle camera shake effect:

https://docs.unrealengine.com/en-US/API/Runtime/Engine/Camera/UCameraShake/index.html

There’s plenty of tuts on YT - you may need to adjust one to your needs as most of them revolve about violent bursts rather than shallow breathing-like effects.

I’m very late to the party here, but maybe there are some assets on the marketplace you could look at, and break down how they’ve done it.

Motion - True First Person Character Template is a first-person framework that comes with breathing (and other camera motions) right out-of-the-box. Seems to be what you’re looking for.