Would be nice if WFS gave us links. Here's what I could find:

• OST 1
  • Amazon (purchase album): https://smile.amazon.com/dp/B075FRMBND/
  • Amazon.co.jp (Japan): https://www.amazon.co.jp/dp/B075FSH2PK/
  • Apple: https://music.apple.com/album/1277568476
  • Google (unavailable): https://play.google.com/store/music/album?id=Bmq5fjofieistkvovvb4a2467ky
  • Spotify: https://open.spotify.com/album/6erIeYuABYwUV7g6SYEdkj
  • YouTube Music: ???
• OST 2
  • Amazon: https://smile.amazon.com/dp/B07GKQG4TD/
  • Apple: https://music.apple.com/album/1428431765
  • Google: https://play.google.com/store/music/album?id=Biu6pt5uksx7zgkt4zdcxrcvrny
  • Spotify: https://open.spotify.com/album/3VdFMG1DDv2you1GoavhpK
  • YouTube Music: https://music.youtube.com/browse/MPREb_QSu6JBs5mY3
• OST 3
  • Amazon: https://smile.amazon.com/dp/B07TBCNLV1/
  • Apple: https://music.apple.com/album/1469362267
  • Google: https://play.google.com/store/music/album?id=Bnevhlyrzwx7z6ejyuxzpmo5fky
  • Spotify: https://open.spotify.com/album/0erMvNlINlPbct63EV4SJ2
  • YouTube Music: https://music.youtube.com/browse/MPREb_iFF49eVOACg
• OST 3, Vol. 2
  • Amazon: https://smile.amazon.com/dp/B082MXV8MS/
  • Apple: https://music.apple.com/album/1491305629
  • Google: https://play.google.com/store/music/album?id=Bv7hamcpjr6623uaidnittkxcly
  • Spotify: https://open.spotify.com/album/5JI8i7qgP9Eu9VAMsTVBJM
  • YouTube Music: https://music.youtube.com/browse/MPREb_2taTbVAxz1X

The first album seems to be missing from many sites, or not available for streaming. The other three are more widely available.

Spotify and YouTube Music offer free ad-supported streaming.