From docs TWIG docs:
Unlike in PHP, it's not possible to break or continue in a loop.
But still:
You can however filter the sequence during iteration which allows you to skip items.
Example 1 (for huge lists you can filter posts using slice, slice(start, length)):
{% for post in posts|slice(0,10) %}
<h2>{{ post.heading }}</h2>
{% endfor %}
Example 2:
{% for post in posts if post.id < 10 %}
<h2>{{ post.heading }}</h2>
{% endfor %}
You can even use own TWIG filters for more complexed conditions, like:
{% for post in posts|onlySuperPosts %}
<h2>{{ post.heading }}</h2>
{% endfor %}