There are 10 Pramanas. Among those, majority of orthodox schools of Hinduism accept at least 3 Pramanas VIZ; Pratyaksha, Anumana and Sabda. Now, do these Pramanas mentioned in the Vedas(Both Karma and Jnana Kanda)? DO the Vedas explicitly say Sabda Pramana should be accepted even if it contradicts Anumana and Pratyaksha?
The Vedas do not mention about PramAnas. It's the Darshana scriptures which talk about them.
For example, in SAmkhya Darshana, three PramAnas (standard) are accepted.
DrishtamanumAnamAptavachanancha sarvapramAnasiddhatvAt |
Trividham pramAnamishtam prameyasiddhih pramAnAddhi ||
Pratyaksha (direct perception), anumAna (inferrence) and Apta VAkya (i.e words of the Rishis or scriptures) - these three standards are accepted in SAmkhya. All other standards are accomplished/established by these three only. By using these three pramAnas the propositions are established.
SAmkhya KArikA 4
Similarly various other PramAnas are accepted in other philosophical systems.
Such enquiries are recorded much later than the Vedas proper (Rig, Yajus, Sama and Atharva) whose subject matter was something else. The term veda should be used carefully and only the four enumerated above.
Now, the concept of pramāṇas developed much later than the Vedas mainly to investigate and understand the Vedic rituals and the Mīmāṃsā system of around the 4th century BCE was the earliest. So logically one cannot expect the concept and its terminology to occur in the Vedas themselves.
The Vedas proper were by themselves one of the few pramāṇas or measures or proofs in the Darshanas as they were treated as self-authenticated.
From the Britannica:
Pramāṇa, (Sanskrit: “measure”), in Indian philosophy, the means by which one obtains accurate and valid knowledge (pramā, pramiti) about the world. The accepted number of pramāṇa varies, according to the philosophical system or school; the exegetic system of Mīmāṃsā accepts five, whereas Vedānta as a whole proposes three.
The three principal means of knowledge are (1) perception, (2) inference, and (3) word. Perception (pratyakṣa) is of two kinds, direct sensory perception (anubhava) and such perception remembered (smṛti). Inference (anumāna) is based on perception but is able to conclude something that may not be open to perception. The word (śabda) is, in the first place, the Veda, the validity of which is self-authenticated. Some philosophers broaden the concept of śabda to include the statement of a reliable person (āpta-vākya). To these, two additional means of knowledge have been added: (4) analogy (upamāna), which enables one to grasp the meaning of a word by analogy of the meaning of a similar word, and (5) circumstantial implication (arthāpatti), which appeals to common sense (e.g., one does not see the sun move from minute to minute, but, as it is in a different place at different times of day, one must conclude that it has moved.