1. Go to https://hidutil-generator.netlify.app/ to create the ~/Library/LaunchAgents/com.local.KeyRemapping.plist file.

Example:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>Label</key>
    <string>com.local.KeyRemapping</string>
    <key>ProgramArguments</key>
    <array>
        <string>/usr/bin/sudo</string>
        <string>/usr/bin/hidutil</string>
        <string>property</string>
        <string>--set</string>
        <string>{"UserKeyMapping":[
            {
              "HIDKeyboardModifierMappingSrc": 0x700000005,
              "HIDKeyboardModifierMappingDst": 0x7000000E3
            },
            {
              "HIDKeyboardModifierMappingSrc": 0x700000065,
              "HIDKeyboardModifierMappingDst": 0x7000000E6
            }
        ]}</string>
    </array>
    <key>RunAtLoad</key>
    <true/>
</dict>
</plist>

2. Notice the <string>/usr/bin/sudo</string>? Yes, now sudo is needed for certain keys. To make this work automatically, need to add to the sudoers file.

   1. Open it for editing via sudo visudo.
   2. At the bottom add <your_username> ALL = (ALL) NOPASSWD: /usr/bin/hidutil

3. To manually load and unload the plist file:

   1. launchctl load -w ~/Library/LaunchAgents/com.local.KeyRemapping.plist
   2. launchctl unload ~/Library/LaunchAgents/com.local.KeyRemapping.plist

4. To manually get and set key remappings:

   1. hidutil property --get "UserKeyMapping"
   2. hidutil property --set '{"UserKeyMapping":[]}' (this clears them)