You are correct. There are indeed some passages in the New Testament that caution against elevating one day over another. One example is in Colossians 2:16-17, where it says, "Therefore do not let anyone judge you by what you eat or drink, or with regard to a religious festival, a New Moon celebration, or a Sabbath day. These are a shadow of the things that were to come; the reality, however, is found in Christ." Here, the emphasis is on not allowing others to judge you according to your observances of religious festivals or Sabbath days.
Similarly, in Romans 14:5-6, which I mentioned earlier, it says, "One person esteems one day as better than another, while another esteems all days alike. Each one should be fully convinced in his own mind. The one who observes the day, observes it in honor of the Lord." Here, the focus is on the individual's own beliefs and practices, rather than on any particular day or season being more significant.
In both cases, the emphasis is on freedom of conscience and not placing too much importance on external practices, including the observance of certain days.