You can control the climb rate on autopilot in two ways.
1: You can use vertical speed, ie; 1000 feet a minute. But you can also use IAS: indicated are speed, let's say you use 164 knots, it will climb the aircraft at 164 knots at all times. Am at work at the moment otherwise I could open FS
and explain it in more detail.
What you also can do is set ias before you take off, sett altitude and hdg, then once airborne hot the AP
button and it will climb at IAS.
Hope this helps a bit.