Change Font size of a label in Lightning field

To change font size of a label in Lightning field, use class attribute and specify font in css like below:

<lightning:select name=”pkAcqName” aura:id=”pkAcqName” label=”Select Organization Name:”
value=”{!v.selectedACQID}” class=”font”>
<option value=”” text=” — — Select — — “ />
<aura:iteration items=”{!v.AcqNames}” var=”i”>
<option value=”{!i.Id}” text =”{!i.Name}” selected=”{!i.Id == v.selectedACQID}”/>
</aura:iteration>
</lightning:select>

.THIS .slds-form-element__label{
font-size: 1.25rem !important;
}