Perhaps something like this —
T1 = readtable('https://www.mathworks.com/matlabcentral/answers/uploaded_files/851315/collated_11.csv')
figure
plot(T1.Datetime, T1.Light)
grid
xlabel('Days')
ylabel('Light')
dl = datetime('29-Nov-2021');
dr = datetime('24-Dec-2021');
interval = days(2);
xtix = dl : interval : dr;
set(gca, 'XTick',xtix)
xlim([dl dr])
.
