Display scaling will revert back to default after reset on Phosh-based OSs such as Mobian, PostmarketOS Phosh, ect.
To make changes permanent the reference configuration needs to be copied to /etc/phosh/ with the scaling for the Pinephone’s display set as desired.
Instructions:
sudo mkdir /etc/phosh/
sudo cp /usr/share/phosh/phoc.ini /etc/phosh/
sudo vi /etc/phosh/phoc.ini
# Uncomment the DSI-1 output section:
[output:DSI-1]
scale = 2
# Change scale to desired value (ex: scale = 1.5 means 150%)
# Save and reboot
Resource: https://gitlab.manjaro.org/manjaro-arm/issues/pinephone/phosh/-/issues/251
Credit: Thank you to Arne from Pinephone Matrix