The Witcher 3: Wild Hunt will let you scale up enemy difficulty in next update, Patch 1.20

Patch 1.20 details released by CD Projekt RED

CD Projekt RED has just released patch notes for the upcoming Version 1.20 for The Witcher 3: Wild Hunt. There's quite a lot to the patch notes including a number of notable improvements. You can get a full list of the patch notes if you head over here, but if you only care about the big stuff, here are the highlights.

  • Adds book titled 'A Miraculous Guide to Gwent' which displays number of gwent cards missing from player's base-game collection and information on where to find them, thus facilitating completion of achievement titled Collect 'Em All. Tome in question can be obtained either from gwent playing scholar in Prologue or from merchant near St. Gregory's Bridge in Gildorf district of Novigrad.
  • Adds option in Options/Gameplay to enable enemy level upscaling. If foes are too easy to defeat due to level difference, upscaling will render them a challenge. Change will not affect experience point gain, loot, or quest rewards. Option can be enabled or disabled at any time, even during combat (however, Vitality/Essence of foes is then fully restored).
  • Improves Inventory navigation when using gamepad. Slots are divided into sections and right stick can be used to jump between them.
  • Improves Crafting panel in merchant shops. Adds option to purchase missing diagram components directly from Crafting panel when talking to merchant, as well as clearer descriptions and option to resize item descriptions.
So pretty much, finding missing Gwent cards is now easier and more intuitive than ever, enemies can be scaled up if you feel like you're overpowered, inventory navigation has been streamlined with a Gamepad (thank you!) and you can also now purchase any items at once from missing diagrams (also a big deal).
 
You have to think that this patch is in preparation for next week's release of Blood and Wine, the final DLC for The Witcher 3: Wild Hunt