I'm not sure if many people realize the the UNHCR has the International Covenant on Civil and Political Rights[0], ratified by ~180 countries. Unlike the First Amendment, the preamble the the ICCPR makes it clear that it is concerned with the responsibilities of States and citizens:
Recognizing that, in accordance with the Universal Declaration of Human Rights, the ideal of free human beings enjoying civil and political freedom and freedom from fear and want can only be achieved if conditions are created whereby everyone may enjoy his civil and political rights, as well as his economic, social and cultural rights,
Considering the obligation of States under the Charter of the United Nations to promote universal respect for, and observance of, human rights and freedoms
Realizing that the individual, having duties to other individuals and to the community to which he belongs, is under a responsibility to strive for the promotion and observance of the rights recognized in the present Covenant
Article 19 of the ICCPR deals with freedom of expression, and states:
1. Everyone shall have the right to hold opinions without interference.
2. Everyone shall have the right to freedom of expression; this right shall include freedom to seek, receive and impart information and ideas of all kinds, regardless of frontiers, either orally, in writing or in print, in the form of art, or through any other media of his choice.
3. The exercise of the rights provided for in paragraph 2 of this article carries with it special duties and responsibilities. It may therefore be subject to certain restrictions, but these shall only be such as are provided by law and are necessary:
(a) For respect of the rights or reputations of others;
(b) For the protection of national security or of public order (ordre public), or of public health or morals.
This frames freedom of expression as a positive right, whereas the First Amendment is about negative rights. Also in contrast to the First Amendment, the power to curtail these rights is explicitly given to law-makers, in a limited fashion. Non-legal restrictions on free expression constitute a violation of rights.
Freedom of speech as defined by the ICCPR is so limited as to be effectively meaningless (which is why ~180 countries have ratified it). It wouldn't protect your ability to report on military misconduct, not wear a hijab, or criticize politicians, for example.
The "public health or morals" clause certainly leaves the door open for abuse. But it's still more useful than talking about the First Amendment as if it applies to the whole world.
I also think it's useful to frame rights both positively and negatively, and to focus on more than just the government's responsibilities.
[0] https://www.ohchr.org/en/instruments-mechanisms/instruments/...