Directx12 would be great. However it would require Frontier to remake the entire game to suit the mechanics for Directx12. Which costs them money. Since only a small percentage of the market actually use Xbox One and Windows 10 (which are inclusive of Directx12), it's not quite in Frontier's interests, financially, to make the game for such a small market.
What's your PC specs?
I know what it's like. HP/Toshiba/ any PC manufacturer selling pre-built systems, tend to stick weak specs in their systems then charge the earth for them, marketing them in sleek nice builds. I have an Xbox One X, and an HP 15'ab222tx (i5,6200U, AMD 370M 2GB [wow, HP put a DEDICATED GPU in a laptop!], 1TB 5400RPM HDD, 8GB DDR3L RAM). When this game was in Alpha, all I got was 1-2fps. Now that is unplayable and decided to invest in my 1st custom desktop PC (specs in my forum signature). And my desktop system does a good job, but it does struggle on the larger parks.
May pay to have at least a quad core processor with a high overclock speed. I have an i7-6700k which is Intel's fastest 6th gen quad core processor (skylake) Intel even labelled it at the time it came out, as their Flagship processor.
It's not as easy to put in a tick box to "Play game in DirectX12 mode" thing. It is costly and more resource/time consuming for a company to change a game meant for Directx11 which more people still use, to Directx12. Granted not everyone can easily afford to throw money at a higher spec'd PC. Got my custom desktop PC from a NZ company (my country) which lets customers customize any of their pre-built systems. They will even...... assemble, build, and test it for you too..... then deliver it to you. It's an Auckland based company
(1stwavetechnologies) which doesn't just give you extremely limited customizable hardware options like Dell and HP, they let you choose whatever CPU/GPU/Storage/RAM/Case you want and provide an 18 month RTB warranty. Some parts like my Samsung EVO 1TB SSD come with extended waranties like a Samsung 5 year warranty too. Rather than sticking with HP's 12 month limited warranty lol.
This game is quite detailed. And since it's a simulation game (simulation games being heavily more CPU intensive), it will lag if you have a weak system or go too craycray and get too carried away with adding things to the game. Otherwise you can try other games out there. I'm leaning towards trying Starlink Battle For Atlas on Xbox One X.