How to make iOS open separate keychain files from macOS
Example ..

Steps to create .p12 file:

Run the Keychain Access Application on your Mac.
Select the login keychain from the top-left panel
Select key's
Right click and select Export Items...
Save your key in the Personal Information Exchange (.p12) file format, and name the file “something.p12”
You will be prompted to create a password that is used when you attempt to import this key on another computer
Enter a password and save