Hello,
I'm a freelance web developer for more than 10 years now.
My opinion about it is:
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half of the potential client have already determined on what technology stack they want to work. You will find job as "Laravel Developer", 'Vue developer", "Angular Developer", ... I never saw an ad saying "Statamic developer"
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the other half, do not care about the technology, they just want a website. So the choice is yours. But don't forget about the market share of a Wordpress...
This is much depending on the type of freelance you want to be. If you want to be more like a "consultant" going to clients (small to huge companies), specialize in some technologies (make a quick look at the jobs ads near you or online). If you want to be "on your own", the main competence you need is sales. Once the website sold, do it like you want, your client will not care.
Hope it helps, Fred