How do I learn to read/write Russian effectively if i already know how to speak it fluently and know almost all constant letters on their own?

All resources seem way too baby-tier and assume that the user has no understanding of the Russian language, but i know how words sound in Russian so I can usually guess what they are even if I don't know how to fully read it. Is there some good resources specifically for this or do I have to start low and try to figure my way out on my own?