user-1: Related question: What opcodes are supported on Liquid but not yet on Bitcoin?
I had seen few opcodes in the slides shared by notgrubles on Twitter. They are:
OP_INSPECTCURRENTINPUT
OP_INSPECTINPUT
OP_INSPECTOUTPUT
OP_TAPTWEAK
OP_MUL64
OP_DIV64
OP_SCALARADD
OP_SCALARMUL

Couldn't find any of these in Bitcoin Core's source code. What does each of these opcodes do and are OP_MUL64 OP_DIV64 the same as OP_MUL OP_DIV?

user101498: You can find a taxonomy and details about the opcodes added in Element's Tapscript in this document. The list is longer than what you have in the OP.
As a usage example, this document details how Elements-Miniscript makes use of some of those opcodes.

-1: <p>Related question: <a href="https://bitcoin.stackexchange.com/questions/109764/what-opcodes-are-supported-on-liquid-but-not-yet-on-bitcoin">What opcodes are supported on Liquid but not yet on Bitcoin?</a></p>
<p>I had seen few opcodes in the slides shared by <a href="https://twitter.com/notgrubles" rel="nofollow noreferrer">notgrubles</a> on <a href="https://twitter.com/notgrubles/status/1407040345867800578" rel="nofollow noreferrer">Twitter</a>. They are:</p>
<pre><code>OP_INSPECTCURRENTINPUT
OP_INSPECTINPUT
OP_INSPECTOUTPUT
OP_TAPTWEAK
OP_MUL64
OP_DIV64
OP_SCALARADD
OP_SCALARMUL
</code></pre>
<p>Couldn't find any of these in Bitcoin Core's source code. What does each of these opcodes do and are <code>OP_MUL64</code> <code>OP_DIV64</code> the same as <code>OP_MUL</code> <code>OP_DIV</code>?</p>
 101498: <p>You can find a taxonomy and details about the opcodes added in Element's Tapscript in <a href="https://github.com/ElementsProject/elements/blob/master/doc/tapscript_opcodes.md#new-opcodes-for-additional-functionality" rel="nofollow noreferrer">this document</a>. The list is longer than what you have in the OP.</p>
<p>As a usage example, <a href="https://github.com/ElementsProject/elements-miniscript/blob/master/doc/extension_spec.md" rel="nofollow noreferrer">this document</a> details how Elements-Miniscript makes use of some of those opcodes.</p>
