This 80k article is pretty good, as is this Cold Takes post. Here are some ways an AI system could gain power over humans:
Hack into software systems
Manipulate humans
Get money
Empower destabilising politicians, terrorists, etc
Build advanced technologies
Self improve
Monitor humans with surveillance
Gain control over lethal autonomous weapons
Ruin the water / food / oxygen supply
Build or acquire WMDs
Note that GPT-4 can already come up with plenty of concrete takeover mechanisms: