Does the preference in Messages > "Keep messages" affect whats stored in iCloud or only whats local on the Mac

In the macOS messages app, there is an option called "Keep messages" that allows you to change the duration for which messages are kept. What is unclear to me is: does this affect my messages stored in iCloud as well or just the local copies on my Mac? I'd like them to stay in the cloud but not my Mac so as to not fill up my MBP's tiny 124 GB HD. I see the option is also there in the iOS Messages settings. Is the choice synced across devices or again does this only affect local device storage and not iCloud.