There’s not a setting for this, but it can be done by adding CSS to admin/customize/themes
.sidebar-wrapper {
.sidebar-custom-sections {
display: contents;
}
[data-section-name="community"] {
order: -3;
}
[data-section-name="categories"] {
order: -2;
}
[data-section-name="custom-section-title-here"] {
order: -1;
}
}