In case others are wondering, here’s how I changed my existing free tier:

• go to instance, select your instance, actions, more actions, edit
• scroll down to VM.Standard.A1.Flex, expand it
• change OCPU and memory
• Save (reboots instance)

CWA nextgen is an active maintenance/bug-fix fork, link: https://github.com/new-usemame/Calibre-Web-NextGen/tree/main

It does have a ‘Primarily AC use” setting in power management, thanks so much for the lead there!