The chart below demonstrates how to paint the background of the chart every 30 minute period on a 2t Renko chart using the PaintBar indicator...
Below is the setup for the PaintBar Indicator. In this case it's setup to Paint Every C#1 Minutes with C#1 dynamically controlled with a Button indicator in top pane of chart. PaintBars also has options to easily paint the overnight vs the day session background different colors.
Chart Definition: https://www.linnsoft.com/charts/paintevery30minutes-esm0