Two express lanes are being added to I-15 in both directions, from Cajalco Road in south Corona to California 60. I don't know if any general purpose lanes are also being added. Project website: https://www.15project.info/project/
I drove through there from CA91 to CA60 a couple of weeks ago, here's a video:
https://youtu.be/tdgE378I7MU
IIRC, this project letting is strictly for the express lanes -- although there's ample room for additional GP lanes as well -- but currently both Caltrans and the Riverside County MPO are assiduously avoiding adding general freeway capacity. My guess is that down the line if the express lanes don't significantly reduce the congestion on the 3+3 I-15 along this stretch, prospective additional lanes may be revisited.