The workflow for altering the number formatting in ARCPro is fiddly and time consuming.
Layer Files (.lyrx) seem to store the number formatting e.g.:
{
"type" : "CIMFieldDescription",
"alias" : "SR",
"fieldName" : "AllData_SR",
"numberFormat" : {
"type" : "CIMNumericFormat",
"alignmentOption" : "esriAlignRight",
"alignmentWidth" : 0,
"roundingOption" : "esriRoundNumberOfDecimals",
"roundingValue" : 2,
"useSeparator" : true
},
but using 'Apply Symbology from Layer' does not update the number format in the target features.
This should be part of the functionality of Apply Symbology from Layer or available.