The seed "5642565127881362006" MIGHT fit your needs with some traveling and some deforestation work.
Spawn is on a desert shore with a view of icebergs.
About 1000 blocks away is a location with a small forest on a plain with icebergs close to shore.
The Amidst map below shows spawn and the Steve icon shows where the screenshot was taken. I was standing on a small beach.
The second screenshot shows the small forest you would have to remove.
The village south of where Steve is has a blacksmith, 2 libraries, church and plenty of fields.
How big a plains area do you need.
I've just found some islands in a frozen ocean.
The truth is I'm looking for something bigger, it's complicated the plains are always in a reduced way, my intention is to build a city in that future area I'm looking for.
I appreciate the previous seed but the space is very reduced. u.u