.wp-block-embed.is-type-video.wp-block-embed-youtube iframe {
  max-width: 850px;
  width: 100%;
  aspect-ratio: 16/9;
  height: 100%;
  margin: 0 auto;
  display: block;
}

.editor-visual-editor .wp-block-embed.is-type-video iframe {
  height: auto !important;
}