Hi Michael,
You can use the 'layoutData' aggregation to restrict this. Here is a sample code
<mvc:View height="100%" xmlns:core="sap.ui.core" xmlns:form="sap.ui.layout.form" xmlns:mvc="sap.ui.core.mvc" xmlns="sap.m"
controllerName="my.own.controller" xmlns:html="http://www.w3.org/1999/xhtml" xmlns:c="sap.ui.commons" xmlns:layout="sap.ui.layout">
<Page title="Hello World">
<form:SimpleForm id="myForm" minWidth="1024" layout="ResponsiveLayout">
<form:content>
<Label text="Name">
<layoutData>
<layout:ResponsiveFlowLayoutData weight="3"></layout:ResponsiveFlowLayoutData>
</layoutData>
</Label>
<Input value="Hello world">
<layoutData>
<layout:ResponsiveFlowLayoutData weight="5"></layout:ResponsiveFlowLayoutData>
</layoutData>
</Input>
</form:content>
</form:SimpleForm>
</Page>
</mvc:View>
Hope this helps!
Thanks and best regards,
Shilpa