Related items of current item by category

Need Help
#1

Hello, I recently started learning octobercms, I’m switching from wp. Following the example of tailor blueprints from the demo theme, I created items and categories. Now I wanted to display items of the same categories as the current item, but I can’t figure out how to do it. Can you explain, help me how to do this, or direct me to where it is written about

#2 
{% if item.categories %}
        <div class="content">
            <h2>Related:</h2>
            <ul class="catalog-item-list" >
                
                {% set output_items = [] %} 
                
                {% for cat in item.categories %}
                
                {% set relateditems = catalog.whereRelation('categories', 'slug', cat.slug).paginate(0) %}
                {% if relateditems %}
                {% for relateditem in relateditems %}
                
                {% if relateditem.slug not in output_items and relateditem.slug != item.slug %} 
                {% set output_items = output_items|merge([relateditem.slug]) %} 
                {% partial 'katalog/item-card' item=relateditem %} 
                {% endif %}
                
                {% endfor %}
                
                {% endif %}
                {% endfor %}
            </ul>
            {% endif %}

Is this a normal solution or is there a more correct one?