It depends mainly on the medicine you use. A good potion won't hurt your hair so much. If you want to find a formal shop, the skill of the hair stylist is also very important.
Softening is actually the first step of ion ironing. If it is straight hair, it can be softened directly. If not, the softening effect may not be good. You can ask the stylist to bring the splint again. It doesn't need to be particularly straight. Do it according to your own preferences, and then you'd better do something like an ion perm. The price is not much higher, it is just a sea.
Reminder: When selecting potions, it is best to look at where he got them and what the packaging is. Some shops choose expensive potions, but they still give you bad ones when they operate in the back, which is a waste of money. So it's best to put the potion outside so that you can see it directly when you use it.