I’ll show you a short clip of me when I was at around 8% body fat.
Anything under 10% is very tough to maintain and very few people actually achieve and even fewer are able to maintain it.
One can still get a clear visibility of six pack at 11–12% %, this is because they have worked hard to make their abs blocky (abs are also muscles and if you use weights to train your abs you can get that look too).
Over time, when you train to stay lean year after year, your hormones get used to you staying at low-body fat and it gets easier to stay like that all year around.
Here is a body fat chart I created that will allow you to figure out what range you currently are in: