toe the line

The Japan Times Online ４月２６日の記事を引用します。
China says chatbots must toe the party line
The Communist Party outlined draft rules that would set guardrails on the rapidly growing industry of services like ChatGPT.

"toe the party line" は慣用句のようです。　新聞記事はタイトルの意味が良く分からなくても記事の本文を読むとたいていの場合意味が分かります。　上記の記事タイトルも本文の最初の段ではっきりします。
Five months after ChatGPT set off an investment frenzy over artificial intelligence, Beijing is moving to rein in China’s chatbots, a show of the government’s resolve to keep tight regulatory control over technology that could define an era.

政府や党などが指示する命令に従うことですね。　"toe the line" で辞書の説明を見ます。

・Oxford English Dictionary: to say or do what someone in authority tells you to say or do, even if you do not share the same opinions, etc.: One or two of them refused to toe the line.
・Collins English Dictionary: If you toe the line, you behave in the way that people in authority expect you to.: He's one of the politicians that wouldn't toe the party line.
・Cambridge English Dictionary: to do what you are ordered or expected to do: Ministers who wouldn't toe the party line were swiftly got rid of.

"toe the line" は "B>toe the party line" の形で使われることが多いようですね。