Eating food can make your blood pressure go up slightly especially if you eat foods that are high in sodium.
The higher sodium intake from high in sodium foods can cause a temporary spike in blood pressure but then a few hours or so later your blood pressure should return to normal.
However most times when you eat food the blood pressure actually drops a little bit because the body directs blood to the stomach and small intestine.
That causes a slight drop in your blood pressure until your food is digested and then your blood pressure should go back up.
Not eating can cause a drop in blood pressure as well so make sure you're eating properly and eating enough.
Most peoples blood pressure does normally drop slightly after a meal but then once the food is digested or within an hour or so of eating the meal your blood pressure should rise again.