One of the headlight bulbs on our Lexus SC430 was being flaky so it was time to replace them both. I found the service manual instructions which are somewhat helpful but not very complete. Here are a couple documents:
https://drive.google.com/file/d/1NlaUwkVvJYIaALVmg7fP8xOTAWIyqbvJ/view?usp=sharing
https://drive.google.com/file/d/1NkQPZQgWxR-FNyt8YJjNZL0uXryKOO_7/view?usp=sharing
There are a couple tricky spots but the main one is a well hidden bolt in the wheel well for the front bumper cover. Otherwise, this takes a bit of time but isn't all that difficult.