Well, <aside> is a semantic element, so it has a special meaning. Quoting MDN reference: “The HTML <aside> element represents a portion of a document whose content is only indirectly related to the document’s main content. Asides are frequently presented as sidebars or call-out boxes.”
So, if this is like a section’s main heading and you only want to put it in <aside> for styling purposes, I would recommend not doing it. You can use CSS to style any element however you want, so even if you put it in something else semantic that maybe better explains its true purpose (like <header>, for example) or a generic <div> element, you’ll still be able to style it differently from the rest of the page and put it wherever you wish