Your pension is not taxed as you save into it.
Once you start using it for income, however, it’s subject to income tax (e.g. 20% on income between £12,501 and £50,000). Here, if you want to keep taxes low in retirement, then naturally you will pay less if you choose to keep your income lower. Yet it’s important to have enough coming in each month to live comfortably. One area where you might be able to exert more control now over pension costs eating into your returns is the management fee on your investments.
It costs money to invest your cash, since this typically goes into funds (e.g. of stocks and/or bonds) which are managed by companies. Yet the amount you pay for each fund does vary depending on the particular fund, whether it is actively managed and the company in question. Here, it might be possible to improve your returns by avoiding funds which charge a high fee - but don’t show value by offering better performance.
If you are contributing to a workplace pension, then your options might be more limited since the scheme likely has “preset” portfolios where the funds are picked for you. However, you can still choose which of the funds within these portfolios you are invested into to try and increase your returns and offset the charges (depending on your appetite for risk).