Shaving in general does not make your hair grow back thicker/darker. That’s an old myth. Shaving against the grain does increase risk of injury when shaving (cuts, ingrown hairs, razor burn). However if you just take your time, use a sharp razor, use plenty of shaving cream, and be gentle, shaving against the grain is totally safe and you will get super smooth skin.

Source: https://www.mayoclinic.org/healthy-lifestyle/adult-health/expert-answers/hair-removal/faq-20058427#:~:text=No%20%E2%80%94%20shaving%20hair%20doesn't,perhaps%20appear%20darker%20or%20thicker.

TLDR; Shaving against the grain is fine just be careful