In Vaadin 23/24 regular ComboBox does not support scroll selected item into view. But with some JavaScript workaround this is possible to do with ComboBoxLight add-on from Directory as unlike ComboBox, ComboBoxLight does not lazy load and hence the target item is in the DOM always.

ComboBoxScrollIntoView.java

package com.example.application.views;

// See: https://github.com/vaadin/flow-components/issues/3470

import java.util.stream.Collectors;
import java.util.stream.IntStream;

import org.vaadin.addons.componentfactory.ComboBoxLight;

import com.vaadin.flow.component.Html;
import com.vaadin.flow.component.combobox.ComboBox;
import com.vaadin.flow.component.html.Div;
import com.vaadin.flow.data.renderer.ComponentRenderer;
import com.vaadin.flow.router.Route;

@Route(value = "scroll-into-view", layout = MainLayout.class)
public class ComboBoxScrollIntoView extends Div {

    public ComboBoxScrollIntoView() {
        ComboBoxLight<String> combo = new ComboBoxLight<>();
        var items = IntStream.range(1, 1000).mapToObj(i -> "Value " + i)
                .collect(Collectors.toList());
        combo.setItems(items);
        combo.getElement().executeJs(
                """
                        $0.addEventListener('opened-changed', (e) => setTimeout(() => {
                          $0._scrollIntoView($0.items.indexOf($0._scroller.selectedItem));
                        }, 100));""",
                combo.getElement());
        combo.setItems(items);
        combo.setRenderer(new ComponentRenderer<Html, String>(i -> new Html(
                "<span style='color: red; font-weight: 700;'><vaadin-icon class='mr-xs' style='fill:blue' icon='vaadin:vaadin-h'></vaadin-icon>"
                        + i + "</span>")));
        add(combo);
    }
}