In general, yes, but it varies by manufacturer so you need to carefully read the manuals for the models you are considering. For example, I just purchased the X4800H. It has 9 channels of amplification. A 7.2.4 setup requires 11 channels just for the theatre zone (not the bar area). With the X4800H you can assign two of the pre-amp outs to two channels connected to a separate stereo amp and use the internal amps for the remaining 9 channels. It uses either the Front, Height 2 or Surround Back pre-outs for this. You will not have amps left for the bar. It does however also have pre-outs for Zone 2 and Zone 3, so a second amplifier could be connected to the Zone 2 pre-out to drive the bar speakers. That's just one scenario. You could also go to a 7.2.2 or 5.2.4 setup, use one set of pre-outs to drive the main speakers on a separate amp and assign one of the Height channel amp pairs for Zone 2 for the bar area.
Put some thought into the bar area. You could run 6 speakers off of a stereo amp but they must be wired properly so that the impedance per channel falls in the 6 to 16 ohm range. You could also get a 3 channel amp and wire each pair of speakers in series per channel and feed it a mono signal. Do you need stereo pairs?
If everttT is right about the impedance of the front speakers, a separate amp is probably a wise idea, especially when faced with using all of the internal amps in the AVR. You'll need to think about how loud you expect to play movies. If playing at reference levels, low impedance speakers will be hard on the AVR. Another thing to keep in mind though is that using a 3-channel amp for the fronts can mean loosing one channel of amplification in the AVR, because the center channel requires only one amp but the other speakers all come in pairs, so you can't use the center channel pre-out and then connect a pair of surrounds or effects speakers instead unless you go for an Auro3D setup that can use a single top speaker.
So there are many options available and adding 6 Zone 2 speakers complicates matters. Careful planning is required for this setup.