If you visit your boyfriend's house for the first time under the guise of formally meeting the parents, and you voluntarily bring a gift and have plans to get married, then you can accept the red envelope from your boyfriend's parents. Your boyfriend's parents giving you a red envelope represents their level of satisfaction with you, and you can communicate with your boyfriend about their specific thoughts afterwards. If you also find this meeting enjoyable, you should formally discuss your marriage with your parents.
If you haven't planned to get married at your boyfriend's house for the first time, it's best not to accept the red envelopes given by your parents. If your boyfriend's parents insist on you accepting it, you can explain to them that you are still in the stage of dating and have no plans to get married yet. If you really get married in the future, it's not too late to accept red envelopes. This not only shows that the girl understands etiquette well, but also enhances her favorability in the hearts of the other party's parents.