Replace text in document using A1 notation as variable names in order to retrieve values stored in those cell references

I have a Google Doc that contains placeholders based on A1 notation like %A1%, %B3%, %A3%, and so on.

In a Google Sheet I have values stored in the cell references that match the variable names.

I want to use a script to replace the text in the document from the spreadsheet.

Example Document

I have a %A1% Doc that %B3% placeholders based on %A3% notation

Example Spreadsheet

Desired Result

I have a Google Doc that contains placeholders based on A1 notation

I have successfully used the following code to make a single replacement but don't know how to loop through all cells in the sheet to make all the replacements.

function myFunction() {  var myDoc = DocumentApp.openById('docID')  var docBody = myDoc.getActiveSection()  var sss = SpreadsheetApp.openById('sheetID');   var x =  sss.getRange("A3:A3").getValues()  docBody.replaceText('%A3%', x)}