Looking for realistic side income ideas

This is a post from my cousin. He's just too shy to post it himself. So, here's the post:

Hey everyone, I’m currently working full-time and want to add a steady side income of around $200–300 per month.

I can dedicate roughly 15–20 hours weekly, have a solid computer setup, stable internet, and I’m fairly comfortable with tech. Also open to picking up new skills if needed.

Ideally looking for something remote or fully online. Could be semi-passive, freelancing, digital work, or anything skill-based as long as it’s consistent and actually doable long-term.

Not interested in quick money schemes, just practical options that people here have seen work.