I am looking to run an experiment; however, I am unable to find an ester that fits what the parameters. A clear ester that is not miscible in water, liquid at room temperature, safe to use and has a density of around 1.2g/cm³?
This page may get you started: Properties of Esters - Chemistry LibreTexts
For low water solubility you may need to start with ethyl propanoate or larger esters.
Ethyl propionate | C5H10O2 - PubChem
It's density is 0.892, so a longer ester may also be desirable to increase that as well.