It would depend. Bash allows for command substitution, so it’s possible that there are commands in a script where you would only know what they would do by running other lines in the script.
Edit: also, this is treading dangerously close to the Halting Problem. Imagine for a moment that you succeeded in creating such a program, written in Bash. Now imagine you gave this program its own source code as input. What would you expect it to tell you?
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