No, they do not delegate the power to lay (set) taxes to the executive, they do assign the executive the function of collecting the taxes laid by Congress.
> Congress doesn’t run the IRS themselves after all
The IRS doesn't freely set taxes, it collects the taxes set by Congress.
Now I'm generally of the opinion that Congress shouldn't be allowed to give the Executive discretion but seems no one agrees with that and Congress would rather let the Executive write "not quite laws" on their behalf.
The quote from the constitution is "The Congress shall have Power To lay and collect Taxes," not for the executive to collect taxes. If they can delegate collecting to IRS in the executive branch, why not can they not delegate the "Power To lay" taxes?