Fixing a faucet that has low water pressure involves a systematic method of trial and error, starting with the easiest fixes first.
The easiest fix is at the faucet, specifically the end of the faucet. At the end of the faucet where the water exits, is a screw-in aerator. This mixes air and water together as the water flows out of the faucet. It has a screen that often gets clogged with debris, sediment, and scale. Unscrew the aerator and see if there is debris clogging up the screen. You can also turn on the water at the faucet to blow out any debris getting ready to clog the aerator. Take note to whether the water flows well when you turn the water on , while you have the aerator removed. Does it flow well at both hot and cold sides or just one? If one side flows well but not the other, you have isolated the problem to that particular side. You can clean the aerator with your fingernail or a brush and some scale remover, or you can buy a new one for cheap.
If the water doesn’t flow well when the aerator is removed, the problem is with the faucet, supply line, or angle valve. The next step would be to determine if the problem lies with the faucet or beyond. Try removing the water supply lines from the faucet. You will need to turn the water off at the angle valve first. With the lines disconnected, point the end of the supply lines into a bucket and turn the water back on. You should have full pressure spraying into the bucket. If you don’t have full pressure, the problem lies either at the supply line, angle valve, or beyond. If you do have full pressure, the problem lies with the faucet itself. You can try replacing the faucet cartridge, or replace the faucet itself if you are looking for an update.
If you have poor pressure at the supply line and/or angle valve, replace them with new parts. You will need to turn off the water to the house for this.