### [Math] How to apply stylistic variants to oper operator?

I am writing an article with set-theoretic formulas.

I found this question which hinted me to the use of the `oper`

operator instead of my ugly workaround for the lack of an "union" or "inter" operator. The basic formula is:

```
oper %Ux222A from {<?>} to {<?>} expression
```

where Ux222A is the Unicode code point for the union symbol (I was lazy to define a new symbol such as `%union`

).

This works fine, but I'd like to have the symbol in bold and somehow bigger. I tried

```
oper { bold %Ux222A} from {<?>} to {<?>} expression
```

but it does not work. The brace becomes the operator and the formula interpretor displays error indicators (inverted question marks) with subsequent items.

**Does anyone know how to apply style variants (bold, size or even color) to **`oper`

operator?

**Update:**

Question closed because plain use of `oper`

gives the expected result.