Hi, Saad! Thanks for the question.
This is possible with Builder. You can make your header/footer a symbol, and any changes made to the symbol will automatically update on every page it is used on.
To convert your header/footer into a symbol, just right-click and select “Convert to symbol”. This will prompt you to give your symbol a name.
Now, you can use your symbol on any page. While in the “insert” tab, select symbols and drag and drop your symbol on the page. You can also select the “symbol” block to use a symbol on your page.
If you want to make changes to your symbol, you can click “edit” on the symbol (on any page) and it will redirect you to the original symbol. Then, you can make any changes you want and it will update on every page it is used.
I hope this was helpful! If you have any questions, feel free to reach back out.