Atlantean city building help

I really want to make a big Atlantis esc city, with a block palette of mostly sandstone and prismirine, made up of great big towers, smaller yet still fairly big houses, boats going around the city on the water (it will be both in the coast and in the sea) small decorations and big sea monsters away from the city but still there it will be called Trident 🔱 Tip and have some lore but mostly I want advice…how the nether do I build this thing?! Do y’all have any tutorials or advice maybe even seeds which would be good for this build (for reference imagine Ldshadowlady’s ocean empire but more sandstone and maybe less pink coral) anything would help thanks!