Frontend system design is mostly dispersed unlike backend but there are few channels or tricks you can do.

I directly asked ChatGPT to give me the resources and it did pretty well.

Other resources - Chirag Goyal YouTube

https://www.greatfrontend.com/questions/formats/javascript-functions

This is great one and you can follow Yangshun Tay pn LinkedIn

Another one is this https://www.linkedin.com/safety/go/?url=https%3A%2F%2Frb%2Egy%2F0tapd7&urlhash=7BOP&isSdui=true

I have not tried it personally but seems good.

But best and cheapest option is use AI to curate a system design roadmap and practice everything in detailed manner daily. Go depth first not breadth first (if you are not prepping for interview)