I think a second route is more beautiful, but i can make an route like this:
 <route id="zenstruck_media_read" pattern="/read">
        <default key="_controller">zenstruck_media.controller:readAction</default>
        <default key="inline">true</default>
        <requirement key="inline">true|false</requirement>
        <requirement key="_method">get</requirement>
    </route>

    <route id="zenstruck_media_download" pattern="/download">
        <default key="_controller">zenstruck_media.controller:readAction</default>
        <default key="inline">false</default>
        <requirement key="inline">true|false</requirement>
        <requirement key="_method">get</requirement>
    </route>