What dscp classes or tos values that have the lowest priority and highest priority?

Yes, there are multiple topics in this forum on that issue, some I believe you participated in in the past. The current hottest approach is qosify.

But please keep in mind that prioritization mostly is a zero sum game, that is for every packet that is treated preferentially another packets is treated worse, which logically implies that you need to be careful to only up-prioritize relative few packets. In the extreme if you put all packets into the highest priority tier the effect is identical to not prioritize any of them.

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