hash of a hash
#1
I have a ripemd160 hash that is the hash of an sha256 hash of plaintext. Is there any way to recover the hex values of the sha256 hash so I can recover the plaintext? To be clear:

1. original plaintext: ???????????? UNKNOWN

2. SHA256 of 1: xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx UNKNOWN

3. RIPEMD160 of 2: KNOWN

My question is how to recover the SHA256 hash?
#2
Your SHA256 hash is a plain-text for RIPEMD160.
So you consider it as a classic password. You know the length (64 characters) and the charset (hexadecimal).
But your problem here is that 64 characters is huge to bruteforce, and probably not in dictionnary.
#3
It is not working like that, instead you need a cracker that supports the algorithm:

RipeMD160 (SHA256 (pass))

where SHA256 output is in hex I suppose

Currently hashcat does not support this format. Where is this format used?