Has anyone had natural-looking forehead fillers?

I am concerned that my forehead looks a bit flatter in profile photos compared to when viewed from the front. I am not sure if it is due to a lack of overall facial volume or the shape of my forehead, but I think my impression would look a little softer if my forehead were naturally rounded. That is why I am looking into forehead fillers.

However, when I look at before and after photos, while some turn out beautifully, others look like the volume is too excessive. I want to look like someone with a naturally shaped forehead, rather than giving the impression that I've had a procedure. I'm worried about whether I can effectively convey the shape I want through a consultation alone, as I think the design that suits different face shapes will vary.

I am curious about the typical starting volume for forehead fillers. While the amount needed varies from person to person, I would also like to know if the cost differs depending on the volume. I am also curious about how long the effects last and what to do if I am not satisfied with the shape later on. I am particularly hesitant to get this done at just any clinic because of stories regarding vascular side effects in the forehead. I feel I need to check their experience and emergency response system; what aspects should I focus on? For those who have received this treatment, was the pain or swelling severe? Please also share some information that would be helpful to convey during the consultation to achieve natural-looking results.