The categories were already bold but we have noticed that you have used the Custom CSS code to make the font weight normal with font size 12px.
please remove the ‘font weight: 400;’ from the code on ‘Appearance > Customize > Additional CSS’.
.post-col .entry-meta .cat-links a {
font-weight: 400;
font-size: 12px;
}
if you didn’t find the above mention code to remove then please paste the below Custom CSS to the end of codes on ‘Additional CSS’ to override the previous code.
.post-col .entry-meta .cat-links a {
font-weight: 700;
}
Thanks