On page 2 of the instructions for form 3115 at https://www.irs.gov/pub/irs-pdf/i3115.pdf it states:
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
Keep in mind that the 3115 is a request. Such request can be denied by the IRS too.
