FreeBSD 12.0 is End of Life and unsupported.
The supported versions here in forums are 12.3-RELEASE, 12.4-RC1 or -RC2 (release candidate), 13.1-RELEASE, 13.1-STABLE.
To get support here in forums, please choose one, I suggest 12.3- or 13.1-RELEASE.
You can download a complete FreeBSD i386 branch package repository easiest from another FreeBSD installation, a online PC, same branch and version. It can be on a USB stick or other external device.
See 
pkg-fetch(8)
	
	
	
		Code:
	
	
		OPTIONS
     -a, --all     Fetch all packages.
     -o destdir, --output destdir
                   Place files in a sub-directory called All of the specified
                   directory.  In this mode, packages are fetched for
                   distribution instead of placing them into the internal
                   cache.
	 
 Example: 
 pkg fetch -o /packages -a. Create a 
/packages directory before executing the command.
But be aware, the offical remote package repository is ~ 100 GB, make sure the device has sufficient space on disk.
For the 'latest" binary packages change in 
/etc/pkg/FreeBSD.conf on the external device from 
quarterly to 
latest.
It's also possible to download only the desired programs. Example:
 pkg fetch -d -o /packages pkg bash xorg xfce4-wm ('pkg' mandatory)
	
	
	
		Code:
	
	
		     -d, --dependencies
                   Fetch the package and its dependencies as well.
	 
 
To install the downloaded packages, boot up the offline PC, mount the external device and execute following commands:
	
	
	
		Code:
	
	
		# cd /mnt/packages/All
# setenv SIGNATURE_TYPE NONE ; pkg add pkg-1.18.4.pkg
	 
 Use 
csh(1) (root's default shell) word complete function for packages names (tab key). Continue 
pkg-add(8) the other packages.