Will I Have a Large Forehead After Brow Lift?

Incision placment determines hairline after browlift. The traditional bicoronal forehead lift where the insicion runs from ear to ear across the top of your head will RAISE your hairline, making your forehead 'bigger.' An endoscopic browlift, which is performed through tiny keyhole incisions behind the hairline, generally will NOT alter your hairline much, if at all. A hairline or tricophytic browlift where the incision is made along the frontal hairline woll LOWER your hairline. Your facial plastic surgeon should take into consideration the shape and position of your hairline in determining which type of browlift is best suited for you.

What you are asking is whether or not your hairline will be elevated thus giving the forehead a larger surface area. This will vary according to the incision placement and the technique utilized.

Yes, you are right -- a traditional coronal brow lift will elevate your frontal hair-line and make your forehead look larger. You may be a candidate for a hair-line brow lift where a strip of forehead skin is removed along the hair-line. This will decrease the apparent size of your forehead - which sounds like what you want.
Of course the trade-off is a more visible scar that runs along the frontal hair-line. If the scar is created properly and you heal well the scar can be hard to notice. However, some patients can develop alopecia (hair loss), hyper/ hypo pigmentation or thickening of the scar.
I recommend that you seek consultation with a Board Certified Plastic Surgeon to discuss the treatment options.