/etc/libreoffice/sofficerc is in libreoffice-common 1:5.2.7-1+deb9u5.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
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HideEula=1
Logo=1
NativeProgress=false
ProgressBarColor=215,7,81
ProgressFrameColor=102,102,102
ProgressPosition=35,153
ProgressSize=444,8
ProgressTextBaseline=145
ProgressTextColor=255,255,255
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