Hi! For the environment concept, I can offer a small first piece: one 2D concept sheet for a single 3D-game location, with an overall scene, palette, lighting and key-prop notes, plus one revision. The indicative price is US$25; final scope, usage rights and delivery would be agreed after reviewing your references.
I use AI-assisted tools for concept work. Here is an existing personal game demo to show the illustrated atmosphere: https://asafdallal.itch.io/lantern-walk-prologue
Could you share one style reference, the first location and your budget?