I don’t use separate profiles (which I reckon are analogous to accounts) - but Firefox does have a feature called ‘Container tabs’ where you can isolate a sessions cookies into a container (default ones are labelled things like Shopping, Personal, Work, etc).

However, I think these are somewhat moot now as I think Firefox handles cookies differently in some way that went over my head - so I’m doing that thing where I post a semi incorrect answer to ensure someone shows up with the correct one.