Hello Aspirant,

See there is no percentage criteria to appear for JEE-Main but as per general rules and regulations,there is requirement of at least 75% marks in 10+2 for General category candidate for admission to NITs/IIITs/CFTIs on the basis of JEE-Main score. 
And the criteria has been relaxed only till this year and for next year it might get restored and if it gets restored then the candidates having less than 75% will not be eligible for admission to aforementioned institutions but they will be eligible to appear for JEE-Main. 

There are some criterion which you need to satisfy in order to appear for JEE-Main so let us discuss them.

JEE-Main eligibility criteria is mentioned below :-

1---   Age criteria   :- There is no age limit to appear in JEE-Main but note that there might be the age limit in any particular institution taking admission through JEE-Main score, so you should keep this thing in mind.
2---   Qualifying Examination   :- To be eligible for JEE-Main one should have passed 10+2 examination with Physics, Mathematics as mandatory subjects along with one of the Chemistry/Biotechnology/Biology/ Technical Vocational subject from any of the recognized central or state board.
3---   Year of qualification   :- For JEE-Main 2023 only those candidates who have passed Class 12 / equivalent examination in 2021, 2022 or 2023; or those who will be appearing in Class 12th / equivalent examination in 2023, would be eligible to appear.

So if you follow all above criterion then you are definitely eligible for JEE-Main.

For more details kindly check out the link given below :-
https://engineering.careers360.com/articles/jee-main-eligibility-criteria

You can also check out the JEE-Main knockout package for preparation of JEE-Main from the link given below :-
https://learn.careers360.com/jee-main-coaching/?utm_source=%20QnA

I hope this information helps you.
Good Luck!!