Here's a list of the different settings server owners or single players can utilise to change parts of the mod.

These settings goes in the file GameUserSettings.ini which is typically located in; ShooterGame\Saved\Config\WindowsServer\
or
ShooterGame\Saved\Config\LinuxServer\
or
steam\stamapps\common\ShooterGame\Saved\Config\WindowsNoEditor if you're on singleplayer.

The default settings

[CastleModifiers]
IsPrimitive=false
CeilingIsFoundation=false
DisableAutoDoors=false
ScaffoldTier=wood
SettlerTier=wood
VillagerTier=stone

In-depth explanation

IsPrimitive accepts true or false. By setting this to true, all original castle tier pieces will have the same damage properties as stone. By default this is set to false and all castle tier pieces will have the same damage properties as metal.

CeilingIsFoundation accepts true or false. True will make ceilings register with the game as a foundation on placement. This means no more "require foundation support" when building long bridges or something like that.

A thing of note is that "is foundation" is applied on placement. Having this set to true and changing it back to false will not affect ceilings already placed. They will be counted as foundations until removed or decayed.

By default CeilingIsFoundation is set to false.

DisableAutoDoors accepts true or false. By default this is set to false, meaning that auto doors have both auto open and auto close. By changing this to true, auto opening and auto closing will be disabled by default. This can still be changed by longholding E on the door and selecting to disable/enable auto open and/or auto close.

ScaffoldTier accepts wood, stone and metal and will set the damage properties accordingly. The default value for scaffold parts is wood.

SettlerTier accepts wood, stone and metal and will set the damage properties accordingly. The default value for settler parts is wood.

VillagerTier accepts wood, stone and metal and will set the damage properties accordingly. The default value for villager parts is stone.

NOTE: You only have to add the settings that you want to change. If you're happy with the default setting, it doesn't need to be in your ini-file.