Additional photos. Forgot to mention we are in northern San Diego (I believe zone 10a)

I think ripping out the concrete and making that a large bed would be very cool and soften the area but for a more affordable option, you could plant something that grows tall and narrow in the existing small bed that is already there. You could plant seasonal color in front of the tall trees/shrubs/whatever. I am not familiar with your climate so don't know what works best in SD. Love your pool and the view!

I would plant tall green stuff in the narrow strip and then use pots to add color and texture. You can layer them and change out what is in them from time to time.