If you have preeclampsia or high blood pressure does ur bp always stay at the same?

I mean like if your bp is at 140/90 or more does it stay the same all day or can it go lower during the day depending on the time or something?? I know very little about this😭 but i been having some symptoms like an on and off head ache every day, vision changes seeing floater,sparks & blurry,but i have no swelling. I went to cvs two times & checked my bp and i guess it has been normal at 128 over something & 132 over something ..i have gd so those symptoms can be contribute to that but idk im scared i might be having blood pressure issues now so thats why im asking this question since i have little knowledge abt this