To add some extra spacing in multiline equation environments (such as align or gather), you can use the \jot command either in the preamble which will affect all your multiline equations, or only locally.
\setlength{\jot}{height}
Here’s an example
\begin{align*}
\setlength{\jot}{12pt}
a + c^3 & = 0 \\
a + b^2 & = 0 \\
d + c^{-1} & = 10 \\
d + a^2 & = \pi
\end{align*}
it looks like this
Voila!
ref: LaTeX Community
Cite as:
Saad, T. "LaTeX: Vertical Spacing in Multiline Equations".
Weblog entry from
Please Make A Note.
https://pleasemakeanote.blogspot.com/2009/02/latex-vertical-spacing-in-multiline.html