• don't use \resizebox!
• prescribe column width and by this allow that cells contents can be broken into many lines.

For example, by use of the tabularray package with libraries booktabs and siunitx (which loads packages of the same name), your tables are:

\documentclass{article}
\usepackage{float}
\usepackage{tabularray}
\UseTblrLibrary{booktabs, siunitx}

\begin{document}

\begin{table}[ht] 
\centering
\begin{tblr}{vlines,
             colspec={Q[l,wd=5cm] Q[c,wd=3cm, si={table-format=-1.2}]}
             }
    \toprule
variable (in log)   & {{{abla blablabl ablabl ab ablabla blablab lablab}}}  \\
    \midrule
bla bla bla blabla blabl abla 
                    & 0.03      \\
ablablab            & 0.29      \\
blabla blabla blablabla bla blablablabla 
                    & -0.47     \\
    \bottomrule
\end{tblr}
\end{table}

\begin{table}[ht] 
\centering
\begin{tblr}{vlines,
             colspec={Q[l,wd=5cm] Q[c,wd=3cm, si={table-format=-1.2}]}
             }
    \toprule
variable (in log)   & {{{ablablab}}} \\
    \midrule
ablablab            & 0.03\\
ablablab            & 0.29\\
ablablab            & -0.47\\
    \bottomrule
\end{tblr}
\end{table}

\end{document}

• don't use \resizebox!
• prescribe the same column width in all tables and by this allow that cells contents can be broken into many lines.

For example, by use of the tabularray package with libraries booktabs and siunitx (which loads packages of the same name), your tables are:

\documentclass{article}
\usepackage{float}
\usepackage{tabularray}
\UseTblrLibrary{booktabs, siunitx}

\begin{document}

\begin{table}[ht] 
\centering
\begin{tblr}{vlines,
             colspec={Q[l,wd=5cm] Q[c,wd=3cm, si={table-format=-1.2}]}
             }
    \toprule
variable (in log)   & {{{abla blablabl ablabl ab ablabla blablab lablab}}}  \\
    \midrule
bla bla bla blabla blabl abla 
                    & 0.03      \\
ablablab            & 0.29      \\
blabla blabla blablabla bla blablablabla 
                    & -0.47     \\
    \bottomrule
\end{tblr}
\end{table}

\begin{table}[ht] 
\centering
\begin{tblr}{vlines,
             colspec={Q[l,wd=5cm] Q[c,wd=3cm, si={table-format=-1.2}]}
             }
    \toprule
variable (in log)   & {{{ablablab}}} \\
    \midrule
ablablab            & 0.03\\
ablablab            & 0.29\\
ablablab            & -0.47\\
    \bottomrule
\end{tblr}
\end{table}

\end{document}