You might try the IRS instructions which in part says "In general, a filer that fails to timely file a Form 3115 will not be granted an extension of time to file except in unusual and compelling circumstances. See section 6.03(4)(b) of Rev. Proc. 2015-13 and Regulations section 301.9100-3 for the standards that must be met. For information on the period of limitations, see section 5.03(2) of Rev. Proc. 2023-1." Here is the link. https://www.irs.gov/instructions/i3115

Here is a link for info on 9100. https://www.journalofaccountancy.com/news/2009/feb/requesting9100relief.html