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Unfortunately there are two things red tip photinias will not stand for - neither one of them evident in your Socal photo-
They will not stand for humidity
They hate being pruned
Most of the people in the USA (including our OP) live in areas with higher humidity than southern California, and most of them want to prune this tree into a 'bush'. That's failure for this plant. Death and disease.
If I were more ambitious Bulldogdad, I'd take and paste a photo of the photinia between the apartment buildings across the street from me. It is more than 6 stories high, never pruned (65 ft maybe?), and in perfect condition. However also in the neighborhood are thousands more photinia which have been hedged and pruned and are diseased, disgusting, and decrepit.
Red tips are not supposed to get anywhere near 6 stories tall, but believe me, they do. This is NOT a plant suited to be a controlled hedge, fails to perform in that expectation, and is highly susceptible to humidity related diseases.
All plants will thrive in the right condition somewhere, and I'm sure the red tip finds those conditions in southern California. The OP is not in southern California.