CentOS - Mar 2021 - CentOS-7-x86_64-dvd-2009.iso is too big for DVD blanks

Supergrub will boot some .iso files.
In the past, I have directly booted a
partition I made from a fedora .iso file.

Another option *might* be making another .iso file.
Mount the file.
Copy its filesystem to a directory.
Remove some stuff you can live without.
Make another .iso file using directions for making a bootable disk.
Burn the .iso file to disk.

-- 
Michael   hennebry at web.cs.ndsu.NoDak.edu
"Sorry but your password must contain an uppercase letter, a number,
a haiku, a gang sign, a heiroglyph, and the blood of a virgin."
                                                              --  someeecards