how to implement different roles in an angular application with JWT

You can use a canActivate guard to implement role-based access to your routes.
First, create a guard using this command ng generate guard yourRoleName
Then, you can check the role and do your logic inside the CanActivate method.
Here is a simple example:

import { Injectable } from "@angular/core";
import {
  CanActivate,
} from "@angular/router";

@Injectable({
  providedIn: "root",
})
export class YourRoleNameGuard implements CanActivate {
  canActivate() {
    const role = localStorage.getItem("role");
    if (role == "YourRoleName") {
      return true;
    }
    return false;
  }
} 

And add this guard for the routes you want to protect in app-routing.module.ts

const routes: Routes = [
  {
    path: "/your-path",
    component: YourComponent,
    canActivate: [YourRoleNameGuard],
  },
]
@NgModule({
  imports: [RouterModule.forRoot(routes)],
  exports: [RouterModule],
})
export class AppRoutingModule {}

You can read more about guards from here