Yeah this all is a mess, but if we restrict ourselves to considering only conformant cables then the problem is at least tractable.

All Type-C to Type-C support 60 W power delivery (3A at up to 20V), some support 100 W (5A at up to 20V) but those can no longer be certified, and the new 240W cables must have a certain logo on them that includes 240W clearly visible (and this means these cables can only be conformant if certified). And how much power a Type-C to Type-C cable can handle is completely orthogonal to the data it can transmit.

USB does allow conforming passive cables that only have USB 2.0 lines, which can support any of the voltages. These can often be differentiated from the cables that support USB 3.x/USB4 by way of the cable being surprising thin, but this becomes harder if it supports more than the minimum 60W.

Passive cables that support USB 3.x can vary in the maximum speed they support, which will also impact some alternate modes. If you want to ensure video support on a passive cable, your best option would be looking for a 0.8m or shorter passive cable that says 40Gbps, as those will all support the maximum currently allowed display-port bandwidth over type-c. [1] But all passive cables that include the USB 3.0 wires should support the lower Displayport 1.x alternative modes.

However, to reduce confusion in the future, USB-IF have recently revamped the rules for certified Type-C to Type-C cables. Cables must be marked with a logo that indicates 60W or 240W. If the cable supports 3.x or newer, it will also marked the max supported speed in Gbps as part of that logo. Failure to use the right logo for what your cable supports will result in failed certification.

Users are expected to assume that that any cable that does not specify wattage only supports 60W (since all USB C-to-C cables support that, except the optically isolated ones, which cannot be mistaken for a normal cable). Users are expected to assume passive cables do not support USB 3.0 data at all unless marked with: 1) a speed in Gbps, 2) a bare SuperSpeed logo (implies a max of 10 Gbps [2]) or 3) marked as Thunderbolt 3 (20 Gbps [3] unless a speed is otherwise shown).

Users are presumably expected to assume that active cables only support 5Gbps unless otherwise marked, and won't support any alternative modes (unless otherwise marked) if not marked as 40 Gbps, in which case DP2.0 alternate mode should work (but I'm not sure that display port 1.x modes are guaranteed to work).

Active cables are also where many problems lie especially as they don't always look different from passive cables. Active cables can mostly only support alternate modes that they were explicitly designed to support which for some is none at all. For example Active gen1 or Gen2 cables don't support USB4 at all. Active Thunderbolt 3 gen3 cables can be used for USB4 by some USB4 devices but this is an optional feature, so not all USB devices and hosts will support this.

Footnotes:
[1] In theory, such cables should be able to handle DP 2.0 at UHBR 20 (80 Gbps) transfers, since they can reverse the 40Gbps return communication lanes, going from 40Gbps bidirectional to 80Gbps monodirectional. However VESA has not yet standardized that as an option.
[2] Since these would probably be gen1 with 5Gbps per lane, and all typeC cables have two lanes in each direction.
[3] Thunderbolt 3 implies gen 2, which as 10Gbps per lane, times two lanes in C-to-C cables.