Hi @msymphony,
Thank you for your question.
You can achieve it by adding the following CSS code in the Custom CSS code option of your theme on the below path.
Admin Area -> Appearance -> Theme Settings -> Custom Code -> CSS Code
@media (min-width: 1250px){
.single-post .container.entry-content {
width: 1250px !important;
max-width: 100% !important;
}
}
Best regards,
Shufflehound team