Use string, not wire
Top Topiary Tip from…
Use string as it gives a little slack and moves with the branch.
Wire cuts into the stems of your plant, potentially ruining the topiary you are making because the cuts may lead to wounds that cause health problems for your plant in the future. And don’t think “well, I’ll just leave the wire on for a little bit, and I’ll definitely return in a few months to loosen it…” because you won’t.
Topiary is important (of course) but life has a habit of getting in the way of important things. You’ll forget the wire and your plant will suffer.
Just use string.