Yes, you can use the Update Issue Field post function to Assign issue automatically.
Ex. When a ticket is created, on create transition add the Update issue Field post function, select the field as Assignee & provide the values that are yourselves.
Like this, you can achieve this for next set of transitions whenever you want to the assignee to the default user.
You must be a registered user to add a comment. If you've already registered, sign in. Otherwise, register and sign in.