I feel something like Mass Effect (mixed BioWare writing aside) is a fine middle ground of having a character creator and also achieving a fully voiced, narratively established protagonist. Having a character creator doesn't mean the protagonist cannot be grounded in the universe in a believable way, even if a fully defined protagonist is preferable.
"Scope" sounds like it's lost in translation too, or misinterpreted. I dunno, folk always seem to think very literally when words like this are thrown around, assuming it means the game is literally bigger in landmass and playable content than The Witcher 3. I don't necessarily feel that's the case. It may be true, but scope can mean so many other things too, like the depth to the title and scope of production. Though I adore The Witcher 3 the questing structure is generally pretty simple, largely due to the defined nature of Geralt's character and available abilities. The game never has to account for Geralt being a master locksmith, or +10 charisma, or anything like that. If CDPR are adopting an assortment of passive game system abilities alongside a multilayered narrative this would in practice of design and development scope be a significant leap over The Witcher 3.
When we look at why CDPR has been so coy on revealing Cyberpunk, and why we hear rumours of a turbulent development cycle, this is likely the reason. As much of a monumental undertaking and achievement The Witcher 3 was, Cyberpunk on paper is an entirely different beast, forcing CDPR to built entirely new game systems from the ground up and quest, world, combat infrastructure to encompass this. The Witcher 3 is more akin to an action adventure RPG where agency is action based and neatly organized through dialogue and combat development. Cyberpunk, if they're leveraging the source material, draws more from traditional PnP rulesets. It'd be like FROM going from making Dark Souls to something like Fallout; plenty of learned experience to leverage, but sweeping differences in design and structure. I can only imagine how much barriers they're hitting seeing this through.
