If your employer offers salary sacrifice, you can agree to give up the part of your salary that you would pay towards your pension, and your employer will pay your contributions for you. Then, you (and your employer) could pay lower National Insurance contributions.
However, there are reasons why this may not be right for you. For example, if you’re with USS for less than two years, and you use salary sacrifice, you’ll still be able to choose to keep pension benefits in USS or transfer them to another scheme, but you won’t have the option to get a refund of contributions when you leave. It may also affect the amount you’re eligible to borrow, if you’re looking for a mortgage or other finance. You should speak to your employer for more details.