With 4.1, I still use these commands inspired by UIThemer’s scripts:
#!/bin/sh
devel-su sed -i 's/theme_pixel_ratio$/theme_pixel_ratio_RENAMED/' /etc/dconf/db/vendor.d/locks/silica-configs.txt
devel-su dconf update
dconf write /desktop/sailfish/silica/theme_pixel_ratio 1.5
dconf write /desktop/sailfish/silica/icon_size_launcher 151.0