Leadership as a warrant in Army Aviation depends on the platform, the mission and the deployment. Oh yeah...and the individual MOS and assignment. We'll leave the whole ship driving part for another discussion somewhere else on the forums (it's been done).
Assault and attack units tend to deploy at the battalion level...and occasionally at the company level. Individual autonomy is limited and leadership is very top-down. Warrants don't lead in this situation, they perform and advise. Medevac deploys as a forward support medical platoon/team with a footprint very similar to an HSL/HSM/HSC small ship det. The OIC is an O-3, but the maintenance officer and standardization officers, who acts as operations, are warrants. They get some leadership experience, but tend to not write NCOERs or have 'command' responsibilities.
Then you have the odd things that happen on deployments...mostly combat. Units get fragmented and small 'dets' form in just about any shithole they are needed. Still, there is almost always an O there for command.
Staff jobs usually reserved for Os in the Navy are often filled with warrants up to and including the brigade level. As a CW3 at the brigade, my counterparts in the Navy I worked with were O-4s. However in my case I was much more successful than my CW4 predecessor and successor because of my previous experience as a Navy O-4.
Then, the national guard has additional special cases. Companies are sometimes broken out across several states. I am a det OIC as a CW4 with 96 people authorized. I have only 55 assigned right now due to the unit being new. On deployment my command status goes away and the company is commanded by an O-4. CONUS I administratively report to an O-5, the battalion commander of the local state GSAB.
TLDR; Army aviation warrants usually are not placed in leadership positions, but there are exceptions.