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I also forgot to mention for the hill cipher- if you didn’t know the key or the the block size used for encryption, there are few ways to go about it.
One of the first things to look out for would be cribs (commonly known plaintext words/phrases). So if you know the text is likely to contain the words “Harry” or “Jodie”, then you can start by experimenting with some combinations of those and form equations and solve them for the entries of the matrix. You can also find the block size by doing some IoC analysis on digrams, trigrams, etc. Unit 87/88 in Madness’ book explains how to attack the hill cipher with cribs in more detail if you’re interested.
The other thing you can also do is to write a brute force algorithm which works well if the block size is small to loop over the invertible matrices and compare the output generated with something like the IoC or quadgram scoring.