Yes... You can file ITR for FY 18-19 up-to 31st July-20 as per extended due date. No more penalty if Your Taxable income less than 2.5 laksh (also nil return).
Thanks all I hope even I can file ITR 4 also nil for FY 2018-19 for proprietor who is going to business next month but wants to file ITR 4 nil for last two FY.