On the "Impact" tab of an Issue, the list of requirements that may be affected is shown, in case the Issue is taken into work. The analysis is based on the similarity of the Issue text and the requirement text. Use this information to locate the requirements that will need to be analyzed and changed.
Also, to identify the requirements that will change if a particular Issue is implemented, use the link from Issues to Functions and from Requirements to Functions. The function page shows links to the requirements that elaborate it. Open the requirements list and study their content for potential changes. This technique lets you locate requirements that are candidates for change without spending much effort.
Turn on the display of effort already spent, so you can estimate the potential effort for development, testing, and documentation if the change is implemented.