This setup is using the NVIDIA kernel module.

Create /usr/share/X11/xorg.conf.d/20-nvidia.conf:

Section "Monitor"
    Identifier "<default monitor>"
    Option     "UseEdidDpi" "false"
    Option     "DPI" "88 x 88"
    Option     "DPMS" "off"
EndSection

Section "Screen"
    Identifier     "nvidia"
    Device         "nvidia"
    Monitor        "<default monitor>"
    DefaultDepth   24
    Option         "Stereo" "0"
    Option         "nvidiaXineramaInfoOrder" "eDP-1-0"
    Option         "metamodes" "nvidia-auto-select @1920x1080 +0+0"
    SubSection     "Display"
        Depth       24
        Modes      "1920x1080"
    EndSubSection
EndSection

Create /etc/X11/Xsession.d/77set_dpi:

/usr/bin/xrandr --dpi 88

Also set the font DPI in System settings/Appearance/Font/Force fonts DPI.