I recently started reading Game Changer, the new(ish) book on Alphazero, and I'm really enjoying it. My one issue so far is that I can't find, in the book or elsewhere, games where Alphazero played the white side of 1. d4 Nf6 2. c4 e6 3. Nf3 d5, forcing a QGD with the knight placed on f3 very early. If anyone knows of any games that went this way, please let me know!
There were a select of games published played between AlphaZero and Stockfish 8, see e.g. here on chess24. Some of them were played without book and some with the TCEC opening book, which I reckon led to a bigger likelihood for the QGD to occur.
Considering that QGD itself is an opening for black, how frequently they occurred in AlphaZero's games playing the white side is mostly dependent on how compliant Stockfish was to playing such systems. As it happened and whether it was directly or by transposition, QGD structures did occur a few times, at least among the ones I can recall/find at the moment, which I will share below along with some other closely related lines that can potentially be of interest to you. Otherwise, and in particular when without a book, Stockfish seemed to favour lines more along Nimzo-Indian and Queen's Indian defense.
Since the games tended to be quite long, I will only include a portion of the starting moves of the games and provide a direct link to each game so you can study the games in their entirety on your own.
- With TCEC openings:
[title "TCEC openings, game 82, AlphaZero vs Stockfish 8 (draw)"]
1.d4 e6 2.c4 d5 3.Nc3 Nf6 4.Nf3 dxc4 5.e4 Bb4 6.Bg5 b5 7.a4 c5 8.axb5 cxd4 9.Bxf6 Qxf6 10.Qxd4 Qxd4 11.Nxd4 Bc5 12.Nf3
[title "TCEC openings, game 85, AlphaZero vs Stockfish 8 (draw)"]
1.d4 e6 2.c4 d5 3.Nc3 Nf6 4.Nf3 Be7 5.Bf4 O-O 6.e3 c5 7.dxc5 Bxc5 8.a3 Nc6 9.Qc2 Qa5 10.O-O-O Be7 11.h4 a6 12.Kb1 Rd8 13.g4 dxc4 14.Rxd8+ Bxd8 15.Bxc4 Nxg4 16.Rg1 Nf6 17.Ng5 g6 18.Bd3 e5 19.h5 exf4 20.Qb3 Qc7 21.hxg6 hxg6 22.Bxg6 Kf8 23.Bxf7 Bf5 24.Ka2
Game 1, Semi-Slav (nearly QGD) mainline, Semi-Slav lines are always closely related to both Slav and QGD due to the rich transpositional lines that exist between them. From move ...12 off-book:
[title "TCEC openings, game 1, AlphaZero vs Stockfish 8 (1-0)"]
1.d4 d5 2.c4 c6 3.Nf3 Nf6 4.Nc3 e6 5.e3 Nbd7 6.Qc2 Bd6 7.g4 Bb4 8.Bd2 Qe7 9.Rg1 Bxc3 10.Bxc3 Ne4 11.O-O-O O-O 12.Be1 b6 13.h4 Bb7 14.Ng5 Nxg5 15.hxg5 Qxg5 16.f4 Qe7 17.Kb1 c5 18.Bd3 g6 19.cxd5 cxd4 20.e4 Rac8 21.Qh2 f6 22.f5 exd5 23.fxg6 hxg6 24.Rh1 Qg7 25.Bc2 Ne5 26.Bb3
- Without book:
[title "Without opening books: game 15, AlphaZero vs Stockfish 8 (1-0)"]
1.Nf3 Nf6 2.d4 d5 3.c4 e6 4.Nc3 c6 5.Bg5 h6 6.Bh4 dxc4 7.e4 g5 8.Bg3 b5 9.h4 g4 10.Ne5 Nbd7 11.Be2 Nxe5 12.Bxe5 Rg8 13.O-O Bb7 14.Re1 a6 15.g3 h5 16.Qc2
The list is by no means exhaustive, you might find more examples by browsing through all the available games.