Speaking to Game Informer, Game Director Carrie Patel from Obsidian clarified it's going to be fairly short in general for an RPG. She said players can expect a similar length to the studio's previous game, the sci-fi The Outer Worlds.
The best comparison for Avowed in terms of scope is The Outer Worlds. Players can expect a roughly similar experience, just like The Outer Worlds, depending on what kind of difficulty they play on, and how thoroughly they explore and invest inside content, versus just sticking to the main crit path missions.
Patel made a similar comment last year, comparing Avowed to The Outer Worlds or Star Wars: Knights of the Old Republic 2. The latter would have been preferable in terms of length since it required over 30 hours just for the main story and over 40 hours when including side content.
The Outer Worlds, on the other hand, is one of the shortest high-profile RPGs around. The main story can be completed in just over 13 hours, while side content doubles that amount to around 26. For comparison, other non-open world RPGs like The Witcher 2 and Dragon Age II require between 24 and 37 hours to complete. With The Outer Worlds, Obsidian had the excuse of a shoestring budget, having picked Take-Two's indie label Private Division as the publisher.