Use a dermaroller with the largest needles, 2.0-3.0 mm, for your body's stretchmarks, but not face. After that apply a self-made vitamin-C serum on it. Don't buy premade vitamin-C serum. Buy vitamin-C separately and mix it with water before you apply it to your skin after dermarolling. You can buy vitamin-C here,
https://owndoc.shop/Dermaneedling/Creams, vitamins, serums, masks/Vitamin C 20 g (0.7 oz)/.
Dermarolling should help with stretch marks, but not of course won't 100% fix it. Laser treatment is more effective, but is much more expensive.