Awareness of what you need to do to visit a foreign destination and what you need to do to come home, in regards to COVID, changes regularly. One of the best resources for that type of information is sherpa. It is easy to navigate, accurate and used by travel professionals.
Other documentation to consider when traveling outside the USA
Visa- Typically in Europe you don't need a visa, but its always good to check. Africa, South America, the Middle East usually require visas. We are seeing more and more electronic visas
Next year we expect a new protocol for visas in Europe.