I’m assuming your sink is the only area having the pressure problem. The most common cause is calcium or other mineral buildup behind your shutoff valves. The second is clogged or collapsed hoses. Shut the water valves under the sink. Remove one line at a time and reopen the valve and allow to run into a bucket. If pressure is low at that point, you will need to shut off the watr to your home, remove the shutoff valve and clean out the clog at that point. If the pressure was good at the valve, replace the flex hoses to the faucett. Good luck with your project.
If your water pressure is only low at your sink, then you must find out why or what is clogging it. Most of that has been covered. One other thing. To have pressure you make your pipes smaller. Here my inlet to my house is an inch or so, then 1/2 inch pipe, then the shutoff valve reduces it to 3/8. If some idiot didn’t reduce the water pipes your water will have no force. My other thought was my first house in St. Louis. I was ready to rehab. The crooked real estate person told me the water was shut off. I assumed he meant turned off. Bad assumption. All the cold water pipes had to be replaced because they were corroded shut. So I learned a bit more about plumbing. . .and it was a good time to go ahead and add those showers I wanted.