Axolotls are illegal in California. Please read this thread for detailed information and links to the actual laws: https://www.caudata.org/forum/f1173-advanced-newt-salamander-topics/f1175-herpetological-science-politics/f1176-laws-legality-ethics/66386-axolotls-illegal-california-here-relevant-laws.html
I always get cool ideas from watching a show called "Tanked" but what I really want to do some day is something like what's shown in the picture I've attached.
When trying to think of how I want to set up a tank it helps me to imagine 1) what I want to see every day when looking at it 2) What my axolotl would like/would interact with and 3) what would make it easier for me to take care of more practical matters such as cleaning and removing waste. I hope you get to have some fun setting up everything and I look forward to seeing what you decide to do with it.
I'll be getting a bigger tank for my axolotl soon, so I've been thinking about some of these things too. I've thought of taking small slate rocks and using silicone to stick them together into a cave, and I was gonna stick a lot of live plants in there, putting a lot of long plants that will reach the top of the water along the back like a background.
Some driftwood in there would also look nice, with some moss on the rocks and driftwood.