Question about PostgreSQL upgrade from version 12 to version 15

[Joseph Kennedy]

Hello everyone,
I'm planning to upgrade my PostgreSQL database from version 12 to version 15 
using pg_upgrade. After completing the upgrade process, I'm curious to know 
whether it's necessary to reindex the database.
Could anyone please clarify whether reindexing is required after completing the 
upgrade process from PostgreSQL version 12 to version 15 using pg_upgrade?
Thank you in advance for your assistance!
Best regards,
Joseph