I want the data above the specified threshold to be colored in the table (in app designer)

d=table2array(app.data);
            d=rmmissing(d);
            [Coeff,P]=corrcoef(d);

            app.UITable5.ColumnName=app.VarNames;
            app.UITable5.Data=Coeff;
            app.UITable5.RowName=app.VarNames; 

            app.UITable6.ColumnName=app.VarNames;
            app.UITable6.Data=P;
            app.UITable6.RowName=app.VarNames;

            nr=size(app.UITable5.Data,1);
            nc=size(app.UITable5.Data,2);
            t=app.TCorrelationEditField.Value;
            for i=1:nr
                for j=1:nc
                    if app.UITable5.Data(i,j)>=t
                        app.UITable5.BackgroundColor(i,j)=[1 0 0];
                    end
                end
            end

[Ankit]

which MATLAB version you are using?

app.OutputTable.BackgroundColor; % this will return the uitable background color

Add style to table or tree UI component - MATLAB addStyle - MathWorks Deutschland - if you are using version 2019a (here you can find some example too