I don't know Coastie, I'm not 100% sure I understand what you're trying to achieve.
Moving the Sensitivity slider all the way to the right (30px) slows the pointer down unless I move it really fast, I think because it now has to move 30 pixels instead of the default 4 pixels before acceleration occurs.
I guess you could also try moving the Acceleration slider all the way to the left if you're wanting to slow the pointer movement down a little.
Is that what you're after?
Or by sensitivity do you mean adjusting touchpad sensitivity, mouse button sensitivity or screen tap pressure sensitivity so more effort is required during the tap/click process to make it work?
I have no idea how to do the latter, though quick websearching of 'linux change touchpad sensitivity' gives results for Linux Mint & a few others, possibly in those results will be a solution?