It should be easy.

If your touchpad is not working

Edit /etc/default/grub to pass kernel parameter (docs):

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GRUB_CMDLINE_LINUX_DEFAULT="i8042.nopnp=1"

Leave other paramters as is. Generate configuration file as normal and reboot.

Make touchpad more useful

Works for most Synaptics and ALPS touchpads. Requires xf86-input-synaptics.

Edit /etc/X11/xorg.conf.d/70-synaptics.conf

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Section "InputClass"
    Identifier "touchpad"
    Driver "synaptics"
    MatchIsTouchpad "on"
        Option "TapButton1" "1"
        Option "TapButton2" "3"
        Option "TapButton3" "2"
        Option "VertTwoFingerScroll" "on"
        Option "HorizTwoFingerScroll" "on"
EndSection

Log out and log in.

More info and parameters

Touchpad Synaptics - ArchWiki

libinput - ArchWiki