I am from Australia. Is it possible for me to learn to speak Spanish fluently (maybe above B2 in terms of CEFR) without relocating to a Hispanic country?
as possible as with any other language, I've never been in any english speaking country but I'd say I'm kind of fluent.
I think you'd be able to find some Spanish expats in Australia since it's a popular destination, maybe you can find some language exchange activities in your town or in couchsurfing.
As a spanish myself I think you might be able to find spaniards in their 20s (probably in their late 20s), even if it's difficult for us to come here, there are programs like work and travel and people who gets work contracts.
however the best would always relocate in a Spanish country.. here you'd be able to find job as english teacher