Lots of “no” on this post.
It sounds like you are wanting to move a scope from one rifle to another. This will require completely rezeroing the optic to the new rifle.
No, you can’t simply move from 100 to 200yrds and expect a 20moa rail to bring a scope zeroed for one rifle at 100yrds to proper zero on a different rifle at 200yrds. There is only ~1.5moa difference between 100 and 200yrds for a 223rem, so a 20moa rail will make far too much change.
Rifle scopes are adjustable because they must be adjusted to uniquely zero on every individual rifle.
THAT SAID....
When using quality optic mounts on a well built rifle, in general you should be able to optically center the scope for windage and elevation (appropriately accommodating an integral zero stop if present, of course), mount onto the rifle, dial the elevation up for the height of the optic over the bore (typically 1.5-2.6”, depending upon mount), and then dial up another 1.5moa. Typically a totally around 3-3.5moa UP from optical center. This will be on paper at 50yrds for a level scope base. For a 20moa base, dial DOWN 16.5-17moa (+3.5moa-20moa = -16.5moa).
So... transferring the scope from the AR to the bolt gun, you should be able to dial off the difference in scope mount height, then add the 20moa correction, and you’d be on paper at 50yrds. Won’t be on target, won’t be zeroed, but it’ll be on paper enough to quickly rezero...
THAT ALSO SAID....
Mount the scope, optically center windage and elevation, dial up 3-3.5moa and you’ll be on paper at 50yrds, and zeroed at 100yrds within 5-8 shots.
Or...
Mount the scope, pull the bolt from the rifle, bore sight the scope on a 25-50yrd target, and you’ll be on target at 50yrds, again zeroed at 100yrds within 5-8 shots.
Or...
Mount the scope, use a laser boresighter to zero the scope ~1.5” high of the dot at 10yrds, and you’ll be on target at 50yrds, again zeroed at 100yrds within 5-8 shots.