How to define a special character to change the style of my inline code?

If you’re using a modern version of WordPress, with the Block Editor, you can add your code in a Code block and then ensure you’re styling the Code blocks:

.wp-block-code code {
    font-family: monospace; 
    display: inline-block; 
    background: #ececec; 
    direction: ltr; 
    text-align: left; 
    padding: 0px 7px 0px 7px; 
}