day by day level of jee main feb attemp

Dear student,
Jee mains will be of similar level for all the days and we cannot predict its difficulty as difficulty is a relative term, something difficult to you might not be difficult for others. Softwares are used to pick up questions from a question bank of similar difficulty level, and if any day the paper is tougher, there won't be much change in percentile, because percentile is a type of relative grading.