That's as dead - or as close to it - as any Yuletide camellia is likely to be. There is no recovery.

While sasanqua camellias are more sun tolerant than most other species, central CA summer sun is a bit too much, especially if soil conditions are not helping. Wants acidic, well drained, fertile and evenly moist soil and planted high or slightly above grade. Lack of adequate soil moisture could be a big factor,

It does not look good. I could not enlarge the picture sufficiently to see if there is any green so the only way to confirm would be for you to very lightly, with your fingernails, scratch the base of the trunk to see if you detect any "green". Green would suggest that the roots are still alive. New foliage does not grow in the summer when it is hot as the plant is slumbering but it may leaf out if the vertical branches are also confirmed to "have green" in a similar manner by looking at where the vertical branching starts, If you get leaf out in the fall or in spring (more common for me), that would be good but it may also decide to throw new trunk or leaf out from the base of the trunk and the recovery effort will be as long as if you had planted a cutting (many years and you would have to regularly prune to develop this tree form. Here in Texas with our hostile temperatures, camellias should be planted to receive direct sun until 11am only, the soil should be evenly moist 24/7 during the summer, mulched with 3-4" all year around and acidified if necessary with any garden sulfur product. They should also be watered during winter if winter is dry: test the soil at a depth of 4" or thereabouts to see if it feels dry, moist or soggy. So inspect what is still "green" and decide what you want to do.