Ho do I underline gap in both side aligned line like this:
\documentclass{article}
\usepackage{cmap}
\usepackage[utf8]{inputenc}
\usepackage[T2A,T1]{fontenc}
\usepackage[english,russian,ukrainian]{babel}
\usepackage{soulutf8}
\usepackage{ulem}
\begin{document}
\textquotedblleft\ul{\mbox{\hspace*{3em}}}\textquotedblright~\uline{\hfill}~\the\year{}~р.\par
\end{document}
but only use \ul{} from soulutf8 package. \ul{\hfill} doesn't work.

\rule[\dimexpr-\dp\strutbox-1pt]{...}{0.4pt)or so. You might need to\smashit as well. – John Kormylo Jun 18 '22 at 18:40\ul{}command work like\uline{\hfill}does. – Konstantin Jun 18 '22 at 23:24