Shrink Trackpad on Macbook running Mojave
The simplest solution I've found which works on any recent version of MacOS is turn off tap to click in System Preferences &gt; Trackpad &gt; Point &amp; Click.

You can use this applescript to quickly toggle tap-to-click on and off. On MacOS open Applications &gt; Utilities &gt; Script Editor and paste the code from this script:

tell application "System Preferences"
    reveal anchor "trackpadTab" of pane "com.apple.preference.trackpad"
end tell
tell application "System Events" to tell process "System Preferences"
    click checkbox 3 of tab group 1 of window 1
end tell
quit application "System Preferences"


Then select File &gt; Export and save in Applications but also make sure to select File Format &gt; Application before saving. 

If you want to make it very easy to run the toggle on and off, you may want to add a custom keyboard shortcut which would just run the toggle application.