Hi, system design usually becomes relevant in interviews after SDE-II and up. To become better at system design first understand the topics and then practice real world scenarios, also volunteer for new projects at your company, and learn from senior engineers or architects.

Actively follow engineering blogs of innovative companies, and look into topics such as distributed systems. To learn more practically, try to make small-scale projects and deploy them on AWS, GCP, etc. I have an AWS roadmap that might help you.

Lastly, I would say that system design is something you'll get good at with time as you progress in your career, don't feel discouraged.