Putting your recommendations into practice by helping clients with implementation is an absolutely valuable skill. Apart from increasing the perceived value of your collaboration, "doing the work" will ultimately make you a more effective consultant. But it's not a requirement to build a profitable consulting practice.
Kevin C. Whelan is a friend and advisor who help marketing consultants sell their heads, not just their hands. He put together a list of ways you can sell your expertise separate from your execution. While some of these are more relevant to those in the marketing space, the vast majority can be explored by consultants in any given field.
- Coaching or mentorship: Retainers, single calls, private or group coaching.
- Knowledge products: Books, online courses, ebooks, audio courses.
- Live training: Workshops, cohort-based courses, webinars and seminars, conferences, individual or group training, lunch and learns.
- Memberships: Content, community, coaching, hybrid.
- Masterminds: In-person, online.
- Content subscriptions: Paid newsletters, paid podcasts, physical newsletters, private podcast subscriptions, limited content series.
- Templates: Checklists, creative, administrative, swipe file.
You can combine some of these together. You can sell them separately. Or you can even bundle them into your consulting engagements and offer a "premium option" with extra value for your clients.
If you're consulting in the marketing space, I highly recommend you follow Kevin's work. Apart from being a prolific creator, he's very a friendly and helpful guy. Here's his website, and here's his Twitter.