How can I connect to power overnight

Plug it in as if you were charging it.

Leaving it on charge overnight is OK.

Use a genuine charging cable and do not let the charge drain to Zero. Keep the iPhone half-charged if you are planning not to use the iPhone for a long period.

The rest is up to you when to charge. how long to charge, how often to charge, which adapter to use starting from 5W to 96W USB-C Power Adapter etc.