setting up custom field automatic assignee

[Mamta Kathuria]

Can someone help on how to assign an automatic assignee for the custom field
this is another custom field other than assignee.

[John Funk]

Hi Mamta - Welcome to the Atlassian Community!

Is this a Team-managed or Company-managed project? 

[Tansu Akdeniz]

Hi @Mamta Kathuria 

Welcome to the community.

Do you mean user picker custom field?

If yes, you can set in workflow via post-function or set rule via Automation (from Project Settings -> Automation). Or add field to request form in a hidden way and use a default value.

[Mamta Kathuria]

Yes, did that 

but for assignee automatic option is there but this custom field even after giving default. Its not there