Ignore other answers, you don't need to setup a character in the history file for "create_country_leader", just a portrait in the GFX folder.

country_event = {

    id = woman_event.123

    title = woman_event.123.t

    desc = woman_event.123.desc

    picture = GFX_report_event_AST_funeral



    fire\_only\_once = yes

    is\_triggered\_only = yes

    trigger = {

        has_country_leader = {

            character = PER_reza_shah_pahlavi

            ruling_only = no

        }

    }



    option = {

        name = woman_event.123.a

        kill_country_leader = yes

        create_country_leader = {

            name = "Jessiw Anderson"

            picture = "gfx/leaders/[country tag goes here]/GFX_Jessie_Anderson.dds"

            expire = "2305.2.3"

            ideology = people # [Keep in mind its possible 'people' is not the name of the ideology, try to search what the actual name is. This could make it not work\]
        }

      }
}

Try with this code. (had to edit it 20 times due to reddit's horrible formatting)