a different story here.
I used to propose like that, sometimes even remotely, but I provide material documents and real cases, some just thousands Impressions a day, some 8M-10M Impressions a day.
On the other hand, I do consulting jobs and take actions upon my clients approval with effort from other team players in client's company. And for every action I proposed, I give clear: Why this action is recommended? What will be impacted? What is the expectation of KPI?
To choose a reliable SEOer, my 2 cents here:
- ask his/her portfolio, any real case? let him/her show the performance diagram from e.g. GSC (a real professional must have some experiences and GSC accounts / screens capture from other clients, ask him/her hide the sensitive data, show some thing you can consider it's real)
- talk with him/her ask some basic and advanced SEO questions, or any special cases?
- ask him/her what's his/her role in the SEO project s/he's been in, how did s/he co-work with other teammates?
- discuss KPI with him/her, ask how long time it can be taken, any potential risk? any challenge?
- do NOT give full control and access to your back-end systems
- you must be the final decision maker before the implementation move to production or content got published
above just for the case if you wanted to find someone as SEO consultant or leading the SEO project, which means the person will work-together with guys in your company on SEO.
But if you want to find someone fully takeover the SEO actions, which means, you just need to pay for it, no anything anyone else will be involved in SEO, (e.g. a programmer in your company need to change coding for TECH SEO, a copywriter need to write content for CONTENT SEO), I haven't heard an agency or freelancer offers the "free" work until seeing the result.