Target individual items of a multi-value field in my page template
There are many ways to achieve this. Given you use a custom or sub-theme you'd follow Twig Template naming conventions and create your own field--node--MYFIELDNAME.html.twig template. And then simply adjust the markup according your needs.

See Classy's field.html.twig for reference and its for-loop you simply can customize:

{% for item in items %}
  &lt;div{{ attributes.addClass(classes, 'field__item') }}&gt;
    {{ item.content }}
  &lt;/div&gt;
{% endfor %}




To target the second item in a multi-value field inside page.html.twig use the following snippet (it starts to count with 0, so that 0 is the first and 1 is the second item).

{{ node.field_MYFIELD.1.value }}