Imposter syndrome is the byproduct of being hyper comparative.
For you can only feel like an imposter if you have other non-imposters to compare yourself against.
The antidote then is to become non-comparative and hyper focused on building up the skills within the identity you want to not feel like an imposter in.
So, rather than compare yourself to the most skilled in your field, focus exclusively on developing the skills of the craft.
Because the cure for what feels like a lack of identity is the accumulation of more actions of someone who would hold that identity. Until eventually, you do it so much that you (finally) become a non-imposter.
This is all to say, if you want to embody the identity of a writer (and not feel like an imposter when you write) just freaking write more—and stop comparing your writing to the greats.