Yes, if unopposed it will be easy.
The overall answer is complicated though.
If you, for example, want to take a third place faction to control of a system (third place in overall influence from the 100% pool that is shared by all the factions and determines, their, er, influence level in the system), then you would push the influence up until it overtakes the second place faction, or you cause the second place faction's influence to fall below your faction. Achieve this by doing missions or other work for your chosen faction, or murdering the ships of the faction you wish to supplant.
Once the influences cross, AND ONLY IF there is an asset in play (something owned by the previously second place faction in the system, such as a station, outpost, orbital POI, planetary base or settlement), then a war will go pending for 24 hours time, at the tick. At the next tick, 24 hours later, the war is on. The rules described above apply and the winner takes the asset. If there is no asset no war takes place and you can then march on to take on the system controller.
After the war with second place is won, OR if the second place faction had no asset, you are now free to keep pushing your influence until you meet the system controller in war/election as appropriate based on govt types. Even if the system owner has multiple assets, the first war will be for the MAIN asset AND full control of the system(!) In order to take any remaining assets you would have to take the risk of allowing them to catch up with you again in influence, trigger another war and win that, hoping they don't manage to take control back and instead you win another asset.
P.S. Only factions of different government types can go to war. Factions of the same government types have elections instead.How easy a faction's influence is to push up or down, depends on the size of the population in a system. For your experiments start with a very small, low population system. That about cover you?