[Solved]-How to use Highcharts regression plugin to plot a trend line using angular 8 wrapper-Highcharts

All you need to do is to install the highcharts-regression package, then import it and initialize it with highcharts (as you did with the exporting module).

import { Component } from "@angular/core";
import * as Highcharts from 'highcharts';

declare function require(name:string);
const HC_Regression = require('highcharts-regression');
HC_Regression(Highcharts);
...

Live demo:
https://stackblitz.com/edit/highcharts-angular-highcharts-regression?file=src/app/app.component.ts