Whats AES-256 max input size? Does the AES-256 encryption standart
have a max input length?

If not, does it mean we can even translate a book to it? Like md5 doesnt care max input length?
AES input size is exactly 16 bytes. But you can apply AES endlessly if you divide your data into a stream of blocks of 16 bytes. – rustyx


rustyx is party right. Just splitting the data is called ECB mode and it is insecure as you can detect repeated plaintext blocks. AES is not a full cipher, it is a block cipher. To create a real cipher from it you need to use it within a mode of operation. To have full CPA security this also requires a unique IV.

The amount of data that can be processed depends mainly on the mode of operation and the width of the block cipher (the block size). Generally modes of operation can handle at least 64 GiB of data in the worst case scenarios (e.g. for authenticated mode of operation such as GCM.