Something along the lines of that code should work if you plotted your data with datetime X data.
daysSinceJanuary1st = randi([0 364], 1, 10)
x = datetime(2021, 1, 1) + days(daysSinceJanuary1st)
h = plot(x, 1:10);
xticks(datetime(2021, 1:12, 1))
xlim(datetime([2021, 2022], 1, 1))
If you want to customize the ticks or the tick labels further, you may need or want to work with the ruler for the X axis directly.
theAxes = ancestor(h, 'axes');
theRuler = theAxes.XAxis
