Hi - Shopify SEO apps will only help with your 'onsite SEO' optimisation e.g. do all your images have alt tags, do your pages all load quickly, do you make correct use of H1, H2, meta descriptions, JSON LD etc. etc. but they can't deal with your 'offsite' optimisation e.g. building backlinks, keyword rank tracking, building domain authority, competitor SEO analysis etc.
Whether or not to hire external help all depends on how much knowledge/time you have to deal with it by yourself. Also, some of the tools you may want to use to really do it properly such as AHREFS, SEM Rush, ScreamingFrog etc. can get quite expensive if just buying them for yourself and are often provided as part of a 3rd party SEO expert service.
I would definitely start with getting your onsite SEO right and then focus on your offsite. But you definitely need both, as onsite SEO on its own won't get you very far.
Also if you go down the expert route, choose carefully, as unfortunately there are a lot of charlatans in the SEO space.
If you are considering picking an on-site SEO app to start with, SEO Master may be your choice. It includes all the features you need for on-page optimization for your store. If you already have one, try out our free SEO check-up, it will give an in-depth report of what you need to do to gain a higher ranking.
Both SEO apps and SEO experts are necessary for your business. They just have different usage at different times of your business.
SEO apps are used when your business is in the initial stages i.e. when you are at a point where you are just new in the market, on that time you should prefer apps that will give you better results in less amount. Some of the SEO tools are Google keyword planners, google trends, rank maths, etc. But when you have gained some space in the market you should definitely contact SEO experts to get in ahead of the queue like we use trending keywords in the content of our website. We PropelGuru as a team also have expertise in Social Engine Optimization. To get more ROI visit our website www.propelguru.com