Within the game of Westbound, you will find several temples which, once discovered, will grant you permanent stat boosts. To increase the boosts granted by a temple you will need to upgrade your desired temple. Temples will be discovered in order when you reach the correct Quest in the correct Series.
On the "expanded menu," (up arrow on the right side of the screen) there is a double up arrow. When you press it a screen will open that says Game Stats Boost.
On that screen are 7 things, the first of which is XP, or Experience Points. It will also be the only one that is not greyed out. When you press it, another screen will open showing the Temple of XP, but it will be greyed out. Temples will become available on the menu as you discover them.
(More are expected)