If Shopify traffic has plateaued for months, outsourcing SEO may help - but...
https://wiki-cafe.win/index.php/What_Do_You_Actually_Get_for_a_$2,500_a_Month_SEO_Retainer%3F
If Shopify traffic has plateaued for months, outsourcing SEO may help - but only if the work tackles the cause, not just adds reports. Ask for Search Console non-branded traffic or organic revenue, and a clear plan for what changes.