Your policy document sets this out. It is common for increases to be linked to an inflation measure such as the increase in the Retail Prices Index (RPI) or the increase in the Consumer Price Index (CPI), subject to a maximum percentage increase.
For any part of your pension where this type of increase applies, if the inflation measure used to calculate the increase is greater than the maximum percentage figure, then the increase applied to that part of your pension will be restricted to the maximum. Please see the example below.