Hi

The concept of percentile in JEE Mains is new and has been started from this year. In 2018, there was no system of percentiles. Further your JEE Advanced rank will determine your admission in Architecture at IITs not JEE Mains Paper 2 Rank.

To check previous year cutoff ranks check this link(this will give you an idea how much this year can go as well) : https://engineering.careers360.com/articles/jee-main-cutoff-for-b-arch-b-planning

Best of Luck.

Hope this helps.

Cheers!