Is it possible to upsize my project plan using the CLI?

I’d like to automate my plan size changes so that I can trigger upsizes and downsizes. Can this be done with the CLI?

Yes, you can do this with the platform subscription:info command. The shortcut for that command is platform s:info, and you can use it like this: platform s:info plan 2xlarge. If you add the -p flag you can specify the project ID. Here are the full details of the command:

platform help subscription:info
Command: subscription:info
Description: Read or modify subscription properties

Usage:
 platform subscription:info [-s|--id ID] [--date-fmt DATE-FMT] \
[--format FORMAT] [--columns COLUMNS] [--no-header] \
[-p|--project PROJECT] [--host HOST] [--] [<property>] [<value>]