How to Get Product Attribute options by attribute code with REST API Magento 2?

You can fetch product attribute options details by REST API with endpoint V1/products/attributes/:attributeCode/options in Magento.

To Access Product Attribute Options, you must have access to the given Role permission,

<resource ref="Magento_Catalog::attributes_attributes" />

You must also need to generate an Admin Token value to pass in the header of the API Call.