As per title, this is not possible in RTJ.

I have seen an idea suggestion on adding new tile, and marked as completed in 2022, but this is not the case as of today.

https://experience.dynamics.com/ideas/idea/?ideaid=6548bec6-941d-e911-9461-0003ff688f46

Could we please have these features:

1. Adding new tile to a live journey (not avaiable in OBM)
2. Edit existing tile on a live journey (currently possible in OBM). This particular one is critical as we do update email tiles with updated dates if the expiry date has passed.

Thanks!