ExampleController.php

<?php
namespace vendorName\pluginName\controllers;

use Craft;
use craft\helpers\Assets;
use craft\elements\Asset;
use craft\elements\Entry;
use craft\web\Controller;

class ExampleController extends Controller {
    public function saveExampleEntry($exampleId)
    {
        $entry = Entry::find()->section('examples')->igdbId($exampleId)->one();
        if ($entry) {
            return $entry->id;
        }

        $data = $this->getExampleData($exampleId);
        $section = Craft::$app->sections->getSectionByHandle('examples');
        $entryType = $section->getEntryTypes()[0];

        $entry = new Entry();
        $entry->sectionId = $section->id;
        $entry->typeId = $entryType->id;
        $entry->fieldLayoutId = $entryType->fieldLayoutId;
        $entry->authorId = Craft::$app->getUser()->getIdentity()->id;
        $entry->title = $data->name;
        $entry->slug = $data->slug;

        $entry->setFieldValues([
            // add custom fields here...
            'someProp' => $data->someProp,
            'anotherField' => $data->anotherField,
            'relatedAsset' => $this->saveRelatedAsset($entry, $data->imageUrl),
        ]);

        if (!Craft::$app->getElements()->saveElement($entry)) {
            return ['status' => 'error', 'errors' => $entry->getErrors()];
        }

        return ['status' => 'success', 'id' => $entry->id];
    }
    
    private function saveRelatedAsset($entry, $url)
    {
        $fieldId = 3; // get the proper field id
        $field = Craft::$app->getFields()->getFieldById($fieldId);
        $folderId = $field->resolveDynamicPathToFolderId($entry);
        
        $asset = new Asset();
        // TODO: need to finish this method.
        
        return $asset->id;
    }
}