I'd recomend reading Demand‑Side Sales 101. I think it will change your perspective of a lot of things and help you sell better and more by helping people.
Try https://www.amazon.com/Demand-Side-Sales-101-Customers-Progress-ebook/dp/B08FRRF68Q
It sounds like it's a book on sales, and it sort of is, but it's also an amazing UX design book. Apply these principles to your client relationships.