How Effective Are Social Media Agency Services for Growing Businesses?

I’m currently researching social media agency services and trying to understand how much value they really bring to growing businesses. Handling content planning, advertising campaigns, audience engagement, and performance tracking across platforms can be quite demanding for a small team. 

Agencies claim to streamline these tasks and improve online visibility, but I’m curious about actual outcomes. Has anyone here collaborated with a social media agency? Did you notice improvements in reach, engagement, or conversions? Any honest feedback, pros, or cons would really help me make a better decision.