I forgot who told me this[1], and I can’t find the thread, but zig init just copies the lib/init directory from your Zig install dir (replacing the placeholder values as well). You can modify the files in lib/init to create your perfect init, then zig init will copy them over.
If you’re like me and you update your Zig often to track the master branch, this becomes a bit more tedious, but still very doable, and, IMO, better than any other third-party tools.
[1] Found it: Default or implicit `build.zig` - #2 by biggest_endian