2500 dollars to spend. Help me make a poor financial decision - Camera upgrade advice

[mmega]

I mostly shoot my kids' sports (high school soccer, so I need outdoor and night under lights)

Current rig- Canon 1DX (16 y.o.) and a Tamron 150-600 f5-6.3 and a Tamron 70-200 f2.8

I have gotten a bonus of 2500 and have earmarked it for an upgrade. Which of the following packages would be best? I only really shoot sports.

Package A:

Canon R6 mark ii (new) + lens adapter+ grip=2500

or

Package B

Canon 1dx mark iii (used)

I want sharpness and lowlight with high fps. I am not getting new glass.

[Waddizzle]

The R6 mark II with a Canon battery grip and Canon control ring adapter.

[EDIT] Do not expect third party lenses to be fully compatible with the advanced focusing and tracking features from the Dual Pixel AF II image sensor.  Your lenses may not keep up with the highest frame rates.

[TomRamsey]

Package A has newer technology which includes autofocus improvements.  Package A weighs a lot less and is physically much smaller.  Package A is a new camera with a warranty, Package B is a used camera, it may have a warranty but it also has mileage.  I have little experience with the R6 Marl II and none with the 1dx mark iii, but I’m always an advocate of buying the newest technology that you can afford.  I feel the R6ii has the autofocus abilities and smaller size that would benefit shooting sports.