Start with an architect and at least a 700K budget. Maybe more. You have a very challenging job site.

$700k include landscaping or just remodel? What are you basing the calculation off of? @sophiewheeler Thank you for your feedback.

Sell and get out of CA! There are other beautiful and more reasonable places to live without the threat of fire and the high cost of living!

I have left CA a few times but I love it here. If I sell I would buy something else nearby.

Then be prepared to spend$$$$ and you need to get an architect to help spend those $$$ wisely.

Canyons are sensitive areas and difficult to work in -- not a DIY project for most people. That said, can you post a photo looking outward to your lower patio area from the steps that descend into the canyon? Kind of hard to comprehend the size and materials of the existing hardscape from the photos shown.

So I agree with the stated budget. The reason it is so expensive is you live on a slope. Non sloped land is less but still it is California so it will still be expensive. With slope you have to get footings that go down to bedrock. Also landscape gets expensive and mind if I mention that retaining wall and structure in your last pic is ..shall we say probably grandfathered in and should be rebuilt with a permited wall/structure if you are doing anything with the space. So there's an added expense too :) .