Installation
Just copy the contents of the zip archive to the mods folder within the game root folder.

Details
Get or set any variable from the console. Variables must be exposed in xml files, ini variables are not visible. 

This mod adds three new commands to the ingame console:

set(variable, value)
Sets a variable to a value. Group is determined automatically. Variable could be referenced by name or by displayName. Value could be a numeric value or an option name.
For example, to set texture quality to uber you can type one of the following commands:
set(textures, uber)
set(Virtual_TexturesOptionVar, uber)
set(textures, 3)
set(Virtual_TexturesOptionVar, 3)


get(variable)
Gets current value of a variable. Group is determined automatically. Variable could be referenced by name or by displayName.
For example, to get current texture quality value you can type one of the following commands:
get(textures)
get(Virtual_TexturesOptionVar)

logVars
Writes all available xml variables to the log file, both names and values. Game should be started with -debugscripts parameter, and the log file is at %USERPROFILE%\Documents\The Witcher 3\scriptslog.txt

I didn't include things to enable debug console and to add all available ini variables to not interfere with other mods.

To enable the console please use Debug Console Enabler mod or just google how to enable it manually.
Some mods like UGOM add new settings to ingame menus - you can set them from the console too.

This is the full list of settings you can use in vanilla game.

• Listed options can be specified as values in set() command instead of a numeric value.
• You can use either names or display names
• SLIDER is a numeric value, TOGGLE can be true/false
  

There are example instructions on how to add all rendering settings from ini files manually if you need them. This is the resulting set. Note that types are not necessarily correct, there are some boolean values present.