I wouldn't worry about bulking it out too much - it is what it is, and whoever is looking at it will see that you've been outside of academia for a few years so it shouldn't count against you (it's not like normal CVs where gaps are suspicious). Just list all the info from your bachelors and masters, including any prizes or extracurriculars, etc, and then put a "professional experience" section and list your work exp - it might be unrelated, but it shows you have people skills, which are handy in sociology! If you've done any volunteering that's relevant to your PhD topic, you can also mention that, and language skills and other qualifications can have a section..
Of course, if you've got time before you apply, you could always look into attending some conferences or workshops or even writing some conference papers or blogposts beforehand - but obviously that's quite time-consuming and might not be feasible. Try not to worry too much - the CV is only a small part of the application. Best of luck :)