DIY vs. Hiring It Out
Some of this you can do yourself. Claiming and filling out your Google Business Profile, asking happy customers for reviews, fixing obvious errors in your business listings, none of that requires an agency. If you have the time and you are willing to learn, doing the basics yourself is a completely reasonable way to start.
Where DIY tends to break down is consistency and volume. Citation building across dozens of directories, writing and publishing content on a regular schedule, monitoring and responding to reviews as they come in, that is a lot of ongoing work on top of running the actual business. Most owners who try to DIY it get the first month done well and then it quietly stops happening for the next six.
A reasonable middle ground is handling the free, relationship-based parts yourself, like asking customers for reviews in person, and paying someone for the parts that take specialized knowledge or eat up real time, like citation building and content.