with a custom field named state reason of type single select want to set his options list based on the issue status value:
ex: if state is pending possible choices for state reason are : 3rd Party, Eng info, Customer Info
if state is Closed : Fixed, Duplicate,Rejected
Take this with precaution, as my expertise and background is quite scarce.
If I understood correctly, you have gone through the Administration pages and enabled a Custom Field of type Select List (single choice). You expect the options of this select list to be dynamic based upon the ticket status value. Well, that's not possible with that custom field.
Can it be made? Sure, but you will need to develop it by yourself or, if you are lucky, find one in the https://marketplace.atlassian.com/. I think you will be lucky, this one may meet your requirements:
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