Row size

Use rowSize property if you are aiming to change all rows sizes. In HTML:

<revo-grid row-size="50"/>

Or in JS:

const grid = div.querySelector('revo-grid');
grid.rowSize = 50;

Individual row sizes

To define individual row sizes use rowDefinitions property.
Size definition is quite straightforward:

const grid = div.querySelector('revo-grid');
const rowDefinitions = [{ type: 'row', index: 0, size: 45 }]; // row with index 0 will receive size of 45px.
grid.rowDefinitions = rowDefinitions;

Demo (opens new window).