@Osheen Mahant IMO you can get into leadership traits nd personality a bit later, initially a better idea would be to prepare a guide or play book for them outlining managerial expectations upwards and responsibilities downwards.
1. What all they are responsible for and not.
2. When to raise a behavioural flag.
3. When to raise a performance flag.
4. What 1:1, checkins and mentoring is needed - can provide standard company formats as examples for weekly monthly quarterly checkins if not using any software
5. Train on doing annual performance appraisal
i am sure if you look into your internal process you can figure out what all you need to put in the handbook for ready reference
As to soft skills leadership traits and other attributes there is a learning curve you can create a resource centre with ideas about articles, topics, books, courses that they can take. HR can recommend such things based on company culture and prioritises for example how to be a remote manager is not a course beneficial for a work from office culture.
Hope this was what you were looking for.