Straighten hair for first time

Hi guys, so I'm thinking about getting my hair done for a special event soon. She claims she has to use a curling iron and other products to get my hair how I want it.

I have never used heat on my hair before. I am afraid it will forever damage my hair!!

Will this once alter my hair texture even a tiny bit?

Should I trust the hair salonist?

(by the way I have naturally very curly hair)