Align font size for tables with different number of columns

I am fairly new to LaTeX and I have a quite basic question. I create tables like this:

begin{table}[H]
    resizebox{textwidth}{!}{%
        begin{tabular}{@{extracolsep{5pt}}lD{.}{.}{-2} D{.}{.}{-2} D{.}{.}{-2} }
            Test & 1 & 2 & 3
end{tabular}}
end{table} 

However, I have a lot of tables and their number of columns differs. Accordingly, the font size changes automatically to my marginal settings (resizebox{textwidth}), i.e. the more columns the table has the smaller the font size. Is there a way to align the font size of all tables at once?

I know that I can decrease the font size manually by increasing the number within extracolsep{5pt} to e.g.

extracolsep{10pt}

However, I don’t want to do this for every table and compare the results until they roughly coincide.

Thanks!

begin{table}[htbp]
     small
        begin{tabular}{lD{.}{.}{-2} D{.}{.}{-2} D{.}{.}{-2} }
            Test & 1 & 2 & 3
end{tabular}
end{table}