It is possible to go supersonic on level flight depending on the altitude, but it is quite ineficient. When accelerating through the transonic region, unload to between zero and +1/2 'g' and use max A/B. Manoeuvre as required once above M1.1 to M1.2
On Mirage III it is forbidden to reduce the engine power at M > 1.6, but is it the same on M2000?