All US citizens can vote in federal elections even if out of the country. See:
Overseas Citizen Voters State and local elections usually require you to state you plan to return to the US to continue to vote in their elections.
Although I myself am not an overseas voter, I trust the expertise of one who founded an overseas voting project
for U.S. citizens, votefromabroad.org, now morphed into the daily political junkie site electoral-vote.com.
It is run by Prof. Andrew Tannenbaum, known for many books and projects with computer networking
(Aside: his Unix-clone MINIX is actually the most widely-used operating system in the world,
exceeding Windows, Linux, MacOS, etc. by virtue of it being embedded on most every
Intel computer chip -- which Intel kept secret for many years.)
He lives in Amsterdam as a retired professor, but votes in California all the time. To wit, from
Wednesday's edition (scroll down to section "B.S. polling" about "push polls"):
Track the election with a red/blue map of the US updated daily using the latest state polls.
www.electoral-vote.com
"One of us, (V), has voted dozens of times in a state (California) where he is no longer a permanent resident, and can assure you it's not a crime, because he doesn't vote in any other state."
So, it at least works for the combination of the Netherlands and California.
[Note added: just saw mod's note -- before this gets whisked off to Off Topic Galore or wherever,
to connect this to Tesla -- the other professor who co-writes electoral-vote.com drives a
non-Tesla EV, but had to cancel publication one day because he got stuck at a non-functional
non-Tesla supercharger site. Stretching; well I tried]