I’ll answer as a curly-haired man who grew up in a family with girls who have straight hair and who took my hair products)
There will be nothing from the shampoo in general, it essentially just washes away the dirt. Moisturizes and nourishes the hair with a balm or mask. If you apply them on straight hair, then yes, they will become softer but will look like icicles, there will be no volume.
In general, products for curly hair tend to soften the hair very much so that you can do some styling and generally cope with stiffness. Therefore, the hair will simply be soft. Most likely, if you are the owner of thin, soft and straight hair, then you will not like the effect of this shampoo: it will crumble a lot. And tau nothing like that
Hello, nothing will happen, since there is no such shampoo that curled straight hair, here it is already necessary to perm the hair. And if you wash curly hair with shampoo to straighten it, nothing will happen either, the maximum will be pleasant to the touch and wavy. In this case, you need to do keratin hair straightening. But in your place it is better not to risk it, most likely, after such a shampoo you will have unruly hair.