Some topping lifts, particularly on smaller boats with not a lot of room for sheave boxes at the mast top, are "fixed" in the manner you describe, but may terminate in a small block on a seized thimble.
You tie some smallish cord (like 1/4 inch) to the bail, and then run it to the block and down to a double block with either a cam cleat or a V-shaped jam cleat.
This is usually enough to put the boom at any desired height. It isn't sufficient to brace the entire mast, however.
There are numerous ways to do this, however. You could run a loop of Dyneema
to the mast top and put a single
block up there. Me, I'm happy with the fixed wire and all the adjustment parts