Hi James…. with some simple CSS code, most definitely. However, are you looking to center “all” page and post titles, or just select areas of your website?
By the way, is it possible to get a link to your site and I will check it out as it relates to your centered title(s) request?
I’m going to take a guess that you want to center your page titles so you can try some custom CSS added to the Additional CSS tab of the customizer:
#page-header .entry-title {
text-align: center;
}