To accurately scale the checkmark with the checkbox, you will first have to rework how AntD positions it. You can do this by changing the checkbox (.ant-checkbox-inner) to a flex layout and then changing the checkmark (.ant-checkbox-inner::after) to be relatively positioned.
After doing this, you should be able to get accurate scaling as long as the scale transform property aligns with the scale factor you are applying. For example, a 32px checkbox would be 2 times the original size of 16px, so we use scale(2). In mathematical terms, scaleFactor = checkboxSize / 16.
.ant-checkbox-inner { display: flex; align-items: center; justify-content: center; width: 32px; height: 32px; } .ant-checkbox-inner::after { transform: scale(2) rotate(45deg); position: relative; top: -6%; inset-inline-start: 0; }