You can use this custom CSS code for overwriting your current width size.
By the way, that width size that currently exists on the site comes from the theme or from a plugin that you have active.
You can control it using this CSS code and you can change the value to what you want, I just found that 61px would be the most in-line with the flag above:
ul.sub-menu {
width: 61px !important;
}
Also, please note that these are considered custom coding work and fall out of the purpose of our support policy, but with small requests like the one here, we are happy to help.
However, if there's ongoing customizations needed or more advanced ones, then we would recommend a front-end developer or a WPML contractor (https://wpml.org/contractors/).
I hope that you will find this information helpful.