You can increase your State Pension income by deferring it. You have to be of State Pension
age to do this. The deal is a pretty good one if you can afford not to take your State Pension now: for each year you defer you get about 10.4% extra income. So if your State Pension is £100 a week and you defer for a year, you can expect to get £110.40 a week
when you do start taking it (plus inflation based increases).
Since 2005 it has also been possible to take a taxable lump sum instead of extra income. This appeals to those who prefer a "bird in the hand". However the deal on offer is nowhere near as attractive: the lump sum paid consists of the income you have given up plus interest
at a rate of at least 2% above the Bank of England base rate. With the base rate at 0.5% this is hardly appetising, although it is probably more attractive than drawing the state pension and keeping it in your current account.