Typing Latex symbol

I have choosen another option, looking the https://ctan.mirror.garr.it/mirrors/ctan/macros/latex/contrib/mathalpha/doc/mathalpha-doc.pdf (mathalfa=mathalpha) package. You can see to pag. 5, 6 and 7 that there are many option for the calligraphic upright characters. For my humble opinion you can choose or scr=boondox or scr=boondoxupr that it is very closer with the image. The font of default of your image is times new roman and hence.....

documentclass[a4paper,12pt]{article}
usepackage{newtxtext,newtxmath}
usepackage[scr=boondox]{mathalfa}

begin{document}
$p$ it is the pressure, and if $mathscr{V}$ is the volume we have:
begin{equation}
    pmathscr{V}=MRT
end{equation}
end{document}

Edit after the comment of the user @Lazy squirrel: I have deleted the blank space between M and R using ! (negative space).

documentclass[a4paper,12pt]{article}
usepackage{newtxtext,newtxmath}
usepackage[scr=boondox]{mathalfa}

begin{document}
$p$ it is the pressure, and if $mathscr{V}$ is the volume we have:
begin{equation}
    pmathscr{V}=M{!}RT
end{equation}
end{document}