Automate a radius on a map in Tableau, to display sites within a certain distance

Hi Freelancers, I'm wanting to create an interactive map in Tableau. Essentially, I have a spreadsheet of different sites and their lat long coordinates. I want to be able to enter in a new lat long position and have tableau draw a radius around this point (at 100m or 500m). I want it to also display the surrounding sites within this radius. I have been doing this in google maps and making the circles in paint (see my atached pictures) but I would really like for the process to be automated... and possibly made into a web-app down the line. Looking forward to hearing from someone who's pretty confident in this sort of task. Cheers Julian