https://community.safe.com/s/article/using-coordinate-systems-within-fme#Transformers
https://docs.safe.com/fme/html/FME_Desktop_Documentation/FME_Transformers/Transformers/csmapreprojector.htm
https://community.safe.com/s/article/which-transformer-do-i-use-to-do-3d-reprojection-v
If you are looking to reproject vertical datums, as of FME 2022.0, there are four transformers, the CsmapReprojector, the GridInQuestIIReprojector, the ReframeReprojector, and updated for FME 2022.0, the EsriReprojector.