The view that the book of Isaiah, as we have it, came from multiple authors has wide support across the spectrum of scholars. Most often, Isaiah is divided into at least three sections: proto-Isaiah (chapters 1-39), deutero-Isaiah (40-55), and trito-Isaiah (56-66).
Proto-Isaiah is generally agreed to come from the actual eighth century BC prophet, Isaiah... with a few caveats. Due to the hyperbolic, quasi-symbolic tone, and the lack of any historical grounding unlike the everything else in Isaiah up to this point, chapters 24-27 are the subject of much debate.
In 2006's The Old Testament: A Historical and Literary Introduction to the Hebrew Scriptures (p 438-439), Michael Coogan said 'most scholars identify [Isaiah 24-27] as an early example of the apocalyptic genre', and (cautiously) suggested that the four chapters likely came from 'the early postexilic period, perhaps in the fifth century BCE'.
More recently, in 2014's Isaiah's Kingship Polemic (p 10), William D. Barker instead stated that 'there seems to be a growing trajectory' that calling the passage an 'apocalypse' is 'misleading and must be abandoned'. He also wrote that 'The majority of scholars on Isa. 24-27 either support an eighth or sixth century date or they favour multiple centuries of authorship and redaction'.
These seem to be saying nearly the opposite ideas are the norm within scholarship: Is Isaiah 24-27 an early sort of 'apocalypse', or is that label 'misleading'? Is Isaiah 24-27 'early' (pre-exilic, possibly from Isaiah himself) or 'late' (post-exilic)? Is there any scholarly preference or consensus on these questions, or are Coogan and Barker both overstating their cases?
What genre(s) does Isaiah 24-27 belong to? When were the chapters most likely to have been written? If redaction took place, when was redaction essentially complete?