If you are referring to the specific proposed amendment from the 1970's, then yes, you capitalize it. If you are referring to the general concept of similar proposals, then you do not capitalize it.
For example:
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to give woman equal rights
The Right to Equal treatment under the law.
It isn’t an amendment, but a law passed in 1965 as the Civil Rights Act.
women
The equal rights amendment caused questions as a result of states revoking their ratification rights. This amendment was finally ratified in 1992 which was more than 202 years after it was first introduced into Congress.