To download Mac OS X 10.11 El Capitan, the most reliable and safe method is using Apple's official support channels
Open the DMG and run the PKG installer inside to place the "Install OS X El Capitan" app into your Applications folder. How to Create a Bootable El Capitan ISO Mac Os X 10.11 El Capitan Iso Download
High-risk ISO alternatives are available via the Internet Archive or GitHub, but these lack official security verification. To download Mac OS X 10
: Use the Apple Support Download Link to get the El Capitan disk image. If you already have 10
If you already have 10.11 and just need the latest version (10.11.6), you can download the 10.11.6 Combo Update Apple Support 2. Creating a Bootable ISO Apple does not provide a direct
: Use the createinstallmedia tool provided by Apple to create a bootable installer on a disk, which can then be converted to a .cdr and renamed to .iso . System Requirements