I want to reduce the Firefox data footprint on my device

I see that the sync feature has caused my device to save 37,841 web pages from across all my synced devices, taking up 1.38 GB of precious memory. I have unchecked the sync browsing history checkbox in settings. I have gone to accounts and sync on my device settings, and all I see is other accounts, with no option to see or add Firefox, so that I can use the switching feature in my device settings to unsync Firefox from this device. What I want to know is, if I clear browsing data on this device, will it clear the browsing data from all my logged in devices? Or will I be okay, since I unchecked the browsing history checkbox in the Firefox settings for sync?