If anyone is interested in further reading, a book I'd absolutely recommend is the Ultimate Isometrics Manual from Dragondoor. It's marketed as being a companion to the Isochain (which is actually an AMAZING product I have used with great success) but all of their information can be used and applied to isometric training in general.
They even have entire sections dedicated to equipment-free and bodyweight isometrics, and much of the information from this post was drawn from that book.