Certainly don't expect for Ryanair to suddenly add the volumes of EasyJet's previous network because of this.
There could well be some expansion, but the slot acquisition will mostly be about giving Ryanair the ability to further optimise its overall slot position, ie taking advantage of the first wave slots for based aircraft and more desirable daytime slots. They may well not use all of them or indeed could drop previous historics in favour of better timed ex EasyJet slots.