Change the colour of p-dropdown items based on a Boolean value

I want to change the background colour of my primeng drop-down items which is dependent on a boolean value that I’m getting from an api and pushing it into a array i.e users

I have a array of objects users which contains 3 fields.
Response of the api is:

users=[{user_name:john.doe,user_id:'J012', is_promoted:true},{user_name:jane.doe,user_id:'J013', is_promoted:false}]
So I was trying to map the users array to get the is_promoted
users.map(u=>u.is_promoted);

If is_promoted is true then the background colour of p-dropdown-items must change to a certain colour.I’m not able to achieve this. Should I try [styleClass]?
CSS:

:host ::ng-deep.p-dropdown-items{
background:darkgrey
}

HTML

<p-dropdown [options]=users optionlabel="user_name" optionvalue="user_id" 
[ngStyle]="{'highlight':users.is_promoted==true}"[(ngModel)]="selectedValue> //Gives an error

I’m able to select the value here. But I need to change the background colour of the dropdown element based on the boolean value. How to approach this?