Are there any good online tools or websites with which someone can gauge their personal risk of contracting covid-19 based on different scenarios (i.e. at place of business, school, etc.)?

No: There are a variety of prognostic tools avaialble to determine personal risk of adverse outcomes if an individual contracts Covid-19, but not one that factors in different scenarios since the variables at each location could be infinite. Here is one to determine you personal risk based on health history https://qxmd.com/calculate/calculator_731/covid-19-prognostic-tool