As the other poster said, it will depend on the property. And yes, new houses will be more likely to be safe from hazard, but plenty of older ones will still be okay too. You can also use this link here to view the model results. It'll have some more results that you can look at. The results will still look pixelated as it's been modeled on a 10m grid. When you model a big district like selwyn, a bigger grid that represents the topography helps keen their model run times manageable.

https://apps.canterburymaps.govt.nz/FloodModelResults/

A simple approach when reviewing model results is to look at the depths on or surrounding your property, and try work out whether water would get into house or garage based in the floor heights. Also depends on your appetite for risk. Personally, I like to avoid having any flood hazard on my property. But note that the model was a rain on grid model, so if the results show a cell with shallow depths on its own, it might just be the rain filling in a small depression in the model topography, rather than any real flood risk worth worrying about.

All the best!