Edit: forgot to hit post, so this response is untimely. Will followup shortly.I am just outside Denver CO. I believe I am under 2021 IPC
Yes, CO uses the IPC per up.codes. Also, CO has adopted the plumbing portion of the IRC, so assuming this is a single family home, your horizontal wet vent would be subject to IRC P3108.1 which requires that any wyes between a fixture drain and the wet vent venting that fixture be horizontal.
UpCodes offers a consolidated resource of construction and building code grouped by jurisdiction
But with the IPC, you do have the option to simplify your lav drain routing, by connecting it directly to the WC drain (with a horizontal wye, not from above), and then connecting the shower drain downstream of that. That assumes that your shower trap arm would be under 8' in length.