There are numerous standards available from organizations (ASTM, ISO, ASHRAE, etc.). Sometimes it's easiest to search the organization's website for relevant standards.
ANSI & ISO standards: Temporary access for COVID-19
ANSI has made some standards available free in response to COVID-19, including 31 ISO standards. Most of the standards are related to technology related to fighting the pandemic.
To access the free portal, individual users must accept the license agreement and register. Once registered, users can return to the portal via https://asc.ansi.org. First time visitors should go to https://www.surveymonkey.com/r/62DZ6TD to register.