Try putting this code in Custom CSS section, it will widen the page title and content section which automatically making them center-aligned.
@media screen and (min-width: 48em) {
.page-two-column .panel-content .entry-header { float: none; width: 100%; }
}
@media screen and (min-width: 48em) {
body:not(.has-sidebar):not(.page-one-column) .page-header, body.has-sidebar.error404 #primary .page-header, body.page-two-column:not(.archive) #primary .entry-header, body.page-two-column.archive:not(.has-sidebar) #primary .page-header { float: none; width: 100%; }
}
@media screen and (min-width: 48em) {
.page-two-column .panel-content .entry-content { float: none; width: 100%; }
}
@media screen and (min-width: 48em) {
.blog:not(.has-sidebar) #primary article, .archive:not(.page-one-column):not(.has-sidebar) #primary article, .search:not(.has-sidebar) #primary article, .error404:not(.has-sidebar) #primary .page-content, .error404.has-sidebar #primary .page-content, body.page-two-column:not(.archive) #primary .entry-content, body.page-two-column #comments { float: none; width: 100%; }
}
It’s worth mentioning that when starting a new project, we’d better use new themes over old ones to better suit the updated WP-core and also for longevity of the project. The new theme (2021) can pretty much display the content any way you want, it’s just a matter of setting it up, doesn’t require editing codes (except in some highly complicated designs).