Hello aspirant , hope you are doing good.

So, the answer to your question is definitely yes. You can get into IITs by first appearing for JEE Mains examination, and only if you qualify in that, you will be eligible to sit for JEE advance examination , and further qualifying in that, with a decent rank, you can get into the IITs.

https://engineering.careers360.com/articles/how-get-admission-in-iits-after-diploma refer this link for more details.

Hope this helps you. Good Luck!