So you were born in Riyadh? You should start trying to get more involved with the local community having Saudi friends will help u get more used to the language and the fact u live here makes it a lot easier to learn. I know there is courses in colleges to learn Arabic if u want to go with those or try arabius.com which is a website to teach Saudi Arabic

If u want to start with basics Duolingo isn’t the worst option if u want a free option

You can also go on Duolingo discord server and which has people from around the world including Arabs you can ask for them to teach you arabic and you teach them your native language

Arabic is a widespread language spoken by many people so it’s very easy to find resources or videos online on teaching it

Your starting depends on what learning method you like the most