Changing the rules for what we mean by 1+1=2 only complicates and prolongs the inevitable conclusion regarding the bigger issue ("Are there absolutes?"😉. This is because whatever rules we establish beforehand (what "1" means, what "+" means, what "2" means, what "=" means), turns 1+1=2 into an absolute according to those rules.
But because we Can change the rules, this means 1+1=2 is not an absolute.
If we are going to change the rules, then we are dealing with "meta-rules" (rules regarding rules). So if we say "We Can change the rules," or "We can Not change the rules," this meta-rule becomes the absolute on a slightly larger scale.
But we can change the meta-rule.
Then we are dealing with meta-meta-rules (rules regarding meta-rules), and (eg) "We Can change the meta-rules," becomes an absolute on a slightly larger scale than previously.
I think you can see where this all leads to: an infinite regression wherein dealing with rules, per se, becomes inevitable and thus an absolute (even to say "There are no rules"--which obviously is not true--is still a (meta-meta-etc) rule.