Chalk circle to the rescue! This is literally just a circle (or triangle or rectangle or hexagon if I'm feeling whimsical) drawn on the carpet with sidewalk chalk. I get a really cheap box of sidewalk chalk at Dollar Tree and keep it handy. The chalk allows you to draw anywhere (assuming you have carpet) and it rubs right out of the carpet. The custodians have NEVER told me that it's a problem and honestly it's usually gone by the time the class is over. It provides a short-term space for the kid and sets them apart. I usually don't draw the circle far from the larger group of kids. Instead I draw it right on the edge of the other kids so that the kid in the circle doesn't feel too left out and doesn't think that they're in something as bad as "time out" (or for me, the "rest chair").
Sometimes I tell the kid "I just want you to have your very own special space so that I can see you doing things right." In those moments I'm trying to set them up for good behavior and then reinforce that behavior later if they do things right. Other times I'll say something like, "I'm gonna let you have some time in your own space over here because you haven't shown me that you can handle sitting next to the other kids." I've heard similar things called "super squares" or "hot spots" but I just call it the chalk circle. Best with Kind and 1st grade I've found.
Chalk circle isn't forever, just for a few minutes. But it gives me a chance to give a kid their own space. Sometimes it's just that little move away from another kid that lets them reevaluate their behavior. In their own space there's nothing to distract them, nothing for them to poke or touch, and nothing to get in their way. Quick, painless, and as soon as they show the appropriate behavior they can leave the circle.