Resign without any offer

Hi all, I am working as a java production support engineer for past 3.8 years with 4.8L . Im trying to switch to java spring boot developer role. But not able to get the calls due to 90 days NP.

Im planning to resign this month end. Is it a good idea to resign without any offer? Also does tcs retain us if we don’t have an offer? I am one of the critical resource in the project.