SHA256 algorithm was invented to generate 256-bit (or 32-byte) hash. They write it will take you several years to crack it. It's true, but there're cases you can brute-force it (for example, with hashcat tool). At least you can try. In this article I'm using openSUSE Linux distro and openCL framework drivers for my NVIDIA GeForce GTX 1060 Mobile graphic card.
Here's an example, how to crack SHA256-hashed password in several minutes using haschat tool.
Let's take a hash of a password, stored in pass.hash file:
$ cat pass.hash