how to replace API url with Run Time Json File Angular 10

Question

currently I am using below structure to get API url

My environment.ts

    export const environment = {
  apiUrl: 'https://12.8.0.1:8282/'

};

I am trying to get apiUrl Using in the Run Time. I did that implementation correctly.

config.service

    import { HttpClient } from '@angular/common/http';
import { Injectable } from '@angular/core';

@Injectable( )
export class ConfigService {
private appConfig;
  constructor(private http: HttpClient) { }

  loadConfig(){
  return this.http.get('./assets/config.json')
  .toPromise()
  .then(res =>{
    this.appConfig = res;
    console.log(res);
  });
  }
  getConfig(){
    return this.appConfig;
  }
}

App module

import { APP_INITIALIZER, NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';
import { BrowserModule } from '@angular/platform-browser';
import { BrowserAnimationsModule } from '@angular/platform-browser/animations';
import { HttpClient, HttpClientModule, HTTP_INTERCEPTORS } from '@angular/common/http';
import { TranslateLoader, TranslateModule } from '@ngx-translate/core';
import { TranslateHttpLoader } from '@ngx-translate/http-loader';
import { AppComponent } from './app.component';
import { AppRoutingModule } from './app-routing.module';
import { AuthGuard } from './auth.guard';
import { NgSelectModule } from '@ng-select/ng-select';
import { ConfigService } from './config.service';
//import {EndDateValidatorDirective} from '../app/layout/admin/holidays/EndDateValidatorDirective'
export const createTranslateLoader = (http: HttpClient) => {

  return new TranslateHttpLoader(http, './assets/i18n/', '.json');
};
const appConfig = (config: ConfigService) =>{
  return() =>{
   return config.loadConfig();
  }
  
  }
@NgModule({
  declarations: [
    AppComponent, 
  ],
  imports: [
    [
      CommonModule,
      BrowserModule,
      BrowserAnimationsModule,
      HttpClientModule, NgSelectModule,
      TranslateModule.forRoot({
        loader: {
          provide: TranslateLoader,
          useFactory: createTranslateLoader,
          deps: [HttpClient]
        }
      }),
      AppRoutingModule


    ]
  ],
  providers: [ConfigService,{
    provide:APP_INITIALIZER,
    useFactory:appConfig,
    multi: true,
    deps:[ConfigService]
  },AuthGuard],
  bootstrap: [AppComponent]
})
export class AppModule { }

I run the project and this is working well. My function executed in the Run time successfully.

Now I need to use this config.json file (inside assets folder) and get that apiUrl. How i do it