To set VAT for your lists, you must first select a country:
Hamburger menu at the bottom right > List settings > Taxes > Country. To display taxes in your active list, open the menu at the top right of the list. Activate Prices incl. taxes.
Once a country has been selected in the List settings, the tax rates can be changed manually. If changes are made here, they can be set as the default, so that they apply to the project you are working on and to all other new projects.