adjusting table columns

You can prescribe column widths with p (or m and b) columns type. For example, you can write your table as:

\documentclass{article} \usepackage{geometry} \usepackage{booktabs} \usepackage{tabularx} \begin{document} \centering \begin{tabular}{ *{4}{>{\raggedright\arraybackslash}p{9em}} } Delikt & Leichte Strafe & Mittlere Strafe & Schwere Strafe \\ Angriff auf einen Geweihten & Brandzeichnung & Blendung oder Abschneiden von Zungen oder Hand & Tod \\ Anstiftung zu Aufruhr & Brandzeichnung & Tod & Tod durch Rädern \\ Aufwiegelung & Bis zu 10 Stockhiebe & Pranger & Verbannung \\ \end{tabular} \end{document} 

which gives

As you can see, in this cases long text in cells are broken into more lines.

original answer However, see, if use of the tabularray package with library siunitx gives acceptable (nicer) result:

\documentclass{article} \usepackage[skip=0.333\baselineskip, font=small, labelfont=bf]{caption} \usepackage{tabularray} \UseTblrLibrary{siunitx} \begin{document} \begin{table}[ht] \centering \caption{Vertical and lateral stresses of mortar.} \label{tab:c} \begin{tblr}{hlines, vlines, colspec = {Q[l, wd=5em] *{3}{Q[c, wd=5em, si={table-format=1.2}]}}, row{1} = {font=\bfseries} } & {{{Item 1}}} & {{{Item 2}}} & {{{Item 3}}} \\ Group1 & 0.8 & 0.1 & 0.1 \\ Group2 & 0.1 & 0.8 & 0.1 \\ Group3 & 0.1 & 0.1 & 0.8 \\ Group4 & 0.34 & 0.33 & 0.33 \\ \end{tblr} \end{table} \end{document} 

Edit: Ups, I wrongly replicate table from answer of @WinnieNotThePooh. Well, it may serv as skeleton for a some similar table with numbers which you like to align at their decimal points.

With your table, which fragment you show in question, a possible solution using tabularray package, can be:

\documentclass{article} \usepackage{geometry} \usepackage[ngerman]{babel} \usepackage{ragged2e} \usepackage[skip=0.333\baselineskip, font=small, labelfont=bf]{caption} \usepackage{tabularray} \UseTblrLibrary{booktabs} \begin{document} \begin{table}[ht] \centering \caption{Vertical and lateral stresses of mortar.} \label{tab:c} \begin{tblr}{ colsep = 3pt, colspec = {@{} *{4}{X[cmd=\RaggedRight]} @{}}, row{1} = {font=\small\bfseries} } \toprule Delikt & Leichte Strafe & Mittlere Strafe & Schwere Strafe \\ \midrule Angriff auf einen Geweihten & Brandzeichnung & Blendung oder Abschneiden von Zungen oder Hand & Tod \\ Anstiftung zu Aufruhr & Brandzeichnung & Tod & Tod durch Rädern \\ Aufwiegelung & Bis zu 10 Stockhiebe & Pranger & Verbannung \\ \bottomrule \end{tblr} \end{table} \end{document} 

The compilation result is:

Better filling of textyou will get if you will reduce font size in table to \small (by adding this command after \begin{table}). In this case table will looks as follows: