Have a great weekend.
Your question is more complicated than that. First, Antioch has Mello Roos and in some areas a number of other special assessment bond districts that may overlap. Mello Roos is based on square footage, but the other assessments are not. They are per parcel assesments for each parcel in a particular subdivision. Brentwood does not have any Mello Roos or assessments that are tied to the square footage of a property. But there are special assessment bond districts for most Brentwood subdivisions built within the last 15 years or so. The assessments vary from subdivision to subdivision, with some costing about $80 a month and others closer to $150 a month. You'll want to research the tax record on the particular property you are interested in to get a clear picture of the assessments.
I hope that helps.