Where to ask clients to leave reviews?

Where do others request clients to leave reviews for their copywriting businesses? And are you simply adding a link to invoices or how are you driving clients there to wherever you're requesting a review?

Most of my clients are on LinkedIn and potential customers are too, but I don't believe there's a place there to leave reviews on a small business.

And I would think Google Business and Yelp wouldn't be relevant to a solopreneur copywriting business.

I have some testimonials on my site, but that would require companies to already know about my business.

I feel with how slow things are suddenly last year and going into this year, I should have been on top of this much sooner, but better late than never and I'd like to make it easy for customers to leave a review or star rating somewhere.

If there's a platform that others are using or can recommend where you're collecting reviews from clients, please let me know.