My SOPs were a little under 800 words when not given a limit (2.25-2.5 double-spaced pages). I described my two biggest research interests in detail, along with two of my other foci in undergrad (highlighting my accomplishments when appropriate but not focusing too much on them), included something about languages (very relevant for Ancient), and then had the paragraph tailored to the individual institution. When I had to make it shorter, I made discussion of my research interests somewhat less detailed, didn't talk about languages, and sometimes cut the bits about other foci.