Hi Jess
You don’t say if you are a UK or US writer, but Sarah is replying to you – so a North American perspective!
Some agents do a lot with New Adult, but we don’t. To be honest, both Polly and I are more comfortable with core YA (so protagonists of 16-18 max). There’s a ton of fantasy around, so we like to have the biggest possible market when going on sub. 
It’s hard to know what we’ve yet to see – until we see it! However, I’m particularly keen to find fantasy that draws on lesser-represented cultures and mythologies (perhaps Middle Eastern or African influences? Eastern European? Caribbean?), especially written by #ownvoices authors. That said, anything that knocks my socks off because of its strong concept and pacy, smart writing is always welcome!
Good luck to you.
Sarah