This is a Free CCNA 200-301 Course that covers the OSI and TCP/IP models. This covers covers knowledge that you need for the CCNA exam, but also for the CompTIA Network+ exam. Learn the fundamentals and basics of networking.
Why do you need to learn the TCP/IP and OSI models? Are they important to know? Yes - you need to know these models for both the CCNA exam, but also for the real world.
People in the real world argue about this, but models like the OSI and TCP/IP help with both understanding and network troubleshooting. Make sure you learn especially the TCP/IP model for the CCNA exam.