To write out an ISO 8601 timestamp in the current language, you can use the date_l10n shortcode:
Writing
{{% date_l10n "2020-10-20" %}}
will result in
20 de octubre de 2020
You can optionally specify a different formatting layout:
For example, the following
{{% date_l10n "2020-10-20" ":date_short" %}}
will result in
20/10/20