Therefore, please explain what you mean, cause not getting it???
With Wireguard we have to define the networks we want to allow communication with. If we are talking server side, it usually is one (very) small range. But if we are talking client side (or if we are connecting two or more sites), it's quite common to have several ranges declared.
Also, I think the OP is mistaking Mikrotik's implementation with wg-quick implementation. With wg-quick the accepted ranges are inserted on the routing table, so no further action is necessary. With Mikrotik the only effect is to allow traffic - we still have to declare the routes, if beyond the Wireguard's interface range.
Also, due to how Wireguard works, I'm not sure it would be a good thing to change on the fly these ranges...
But That's what I understood from the OP request.