I have called a lot of Sika in over the years. Not as easy as calling Roe in my opinion.
First of all know your ground, and the beast itself. I have always found its best to be higher. Find a slight hillock and sit down against a good sized tree. Wind in your face, of course.
Set your sticks up and rifle ready. Sika pick up every movement, and when they often come to the call they are suspicious, especially the old stags. I have seen them creep along or down a bank like a cat hunting.
Make the call loud and precise, tailing off at the end. Then wait a good few minutes. Sometimes if a stag is in the area, or your on his patch he will call back. If so call again with the call, then leave it and just watch the area to the side and in front. In fact even behind if you can. I have had stags creep in up wind to see what is going on and also how big a stag I might be.
If you get a chance at a shot, nail the stag in the shoulders. Pound to a penny they will know what you are as soon as you bring the rifle to bare on it. Shoulder shot should put it down, or at least it should'nt run too far.
Finally if a bigger stag twigs you, he will think twice about coming back again. Dont call from the same place, move to another spot nearby. But it is exciting calling them in, and over the years I have had some great moments calling Sika stags in the rut.
I should add that most of my Sika stalking has been in Scotland, for this year about 38 consecutive years, apart from Covid year before last. But I have also shot them for about 7 years in the West country, near Dorchester. To me they are two different animals. Scottish Sika seem to be more on the ball, probably because they dont see so many people, and are disliked by the FC, who wage a continuous campaign against them.
Good luck