@Neha Tyagi, I would actually suggest taking a more focused approach.
1. Identify some of the critical roles in each function you are targeting. (The critical roles can be based on multiple factors that calculate their value - it is not always necessary that senior roles will be more critical)
2. For each critical role, evaluate the behavioral and the technical competencies needed. (For example, to be a CFO, someone might need 'Business Acumen' as behavioral knowledge and 'Tax laws' as technical)
3. Identify proficiencies needed for each competency at each level. (For example, if there is a role of Accountant in Finance, it would be good for them to have 'Financial Acumen' but not at the same level of expertise as the CFO)
4. Evaluate the competencies and proficiencies of the people who you think can fit into the CFO role if the role is vacant. (The ideal way to identify these people would be using the process that @Ashish Vyas described - after identifying the job levels and the career trajectories)
5. Figure out what learning path each person will need to be succession ready and how much time they will take.
6. Pilot test the succession plan and after making adjustments, launch it to the wider world.
I hope this helps, otherwise feel free to DM.