/usr/share/games/openttd/scripts/on_server.scr.example is in openttd-data 1.5.3-1.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 | echo "Setting default network server settings..."
net_sync_freq = 100
net_frame_freq = 0
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