I would say that there is more manipulation in straightening than just scrunching, plus I believe there is no way to make your hair "curlier" with products. I think it just enhances what your hair can naturally do. My hair curl pattern does't change without products, but it sure is frizzer.
For example, if your hair isn't moisturized and is dry, and your curls appear limp. Does adding a moisturizer or product to your hair change the way your curls may appear? Yes (giving it spring and bounce) , but does that mean the hair cannot naturally do that on it's own if it were moisturized? I don't think so.
Originally Posted by Always@night
There is a way to make *some* hair types appear curlier or straighter with *some* products and it is much the same process as straightening or using a curling iron, strengthening or weakening protein bonds, drawing the water out of hair. However you can't go up or down so many levels with products alone, and I suspect this effect is way more obvious with looser wave patterns.
Magnesium Sulfate: Curly Friend or Foe?

To me moisturising/ conditioning is somewhat different. Oftentimes that returns the hair closer to the natural or virgin state (no chemical treatment, affecting colour or curl pattern), without so much of the damage and dehydration we cause in daily life. Even those of us with natural/ chemical free/ heat free hair have often used products or techniques that mean we are not truly virgin, but damaged by shampoos or brushing to distribute oils. Personally I get more definition and clumping from basic conditioners, rarely more curl as such.
2a-2c, medium texture, porous/ colour treated. Three years CG. Past bra strap length heading for waist.

CO-wash: Inecto coconut/ Elvive Volume Collagen
Treatments: Komaza Care Matani, coconut/ sweet almond/ fractionated coconut oils, Hairveda Sitrinillah
Leave in: Fructis Sleek & Shine (old), Gliss Ultimate Volume, various Elvive
Styler: Umberto Giannini jelly, Au Naturale styling gelee
Flour sack towel, pixie diffuse or air dry.
Experimenting with: benign neglect