Software evolves. The ecosystem evolves. You have likely reached the point where your OS has evolved beyond its ability to support a 20-year old application.
Have you tried backing out Windows updates? This is a royal PITA. How much time are you willing to waste on this?
Sure, I can install O365 but sinv=ce I write VB6 code and interface it with Excel, Word and Access, I cannot use any newer Office product.
Why do you think your other code will break? Generally it will upsize. Just make sure you have clean compiles BEFORE you attempt to upsize.
What platform are you using to write your VB6 code? All the Office apps use VBA. They do not use VB6 so we really don't know what you are doing.
From what you have said, you are not actually using Access. Access is a Rapid Application Development tool that is used to build applications. Jet (.mdb) and ACE (.accdb) are the closely coupled database engines. They are used to hold the Access application objects and in some cases may also be used to hold data for an Access or other application. If all you have in your "Access" database is tables, then you are technically not using Access. Access in your case, is merely the GUI for creating tables. That can be done in VB6 using DAO or ADO. You don't even need to have "Access" installed. I'm pretty sure VB6 can use ADO.
I don't believe we can help you. You have locked yourself in a room and seem to have lost the key.
Unfortunately there is a HUGE interface change between A2003 and A2007 for all the Office apps so that would be a pretty steep learning curve. You will be climbing that hill sooner or later. Under duress (as it now seems) or in a planned conversion (seems to be that ship has sailed). When you install O365, you will be at A2019 at least. Do not under any conditions try to go just to 2007. Newer versions are far better than 2007.