Need to check via if condition that variable named "var" contains the contents of variable "value" and "var" must have more than 113,469 characters

Question

Check via if condition that variable named "var" contains the contents of variable "value" and "var" must have more than 113,469 characters above described conditions are met, the script must then print last 20 characters of the variable "var".

I am stuck at this question from a HTB Academy tutorial and tried out by different ways but still no luck with solution. Any help?

#!/bin/bash
var="8dm7KsjU28B7v621Jls"
value="ERmFRMVZ0U2paTlJYTkxDZz09Cg"
for i in {1..40}
do
        var=$(echo $var | base64)
        
        #<---- Need to frame an if condition here:
done