Just to add the following: The EU is recognized as the second largest economy globally after the USA.

That however was before the UK left; the EU lost 16% of it's GDP upon the UK leaving and 13% of it's population.

Should the UK join CPTPP ( and all the evidence to date suggests that this is likely - and likely quite soon too ) then the CPTPP would overtake the EU as being the second largest economy and what is more, this is predicted to soon overtake the USA to become #1.

Trump had a chance of being a member in the TPP days but withdrew, so he's certainly not a supporter - which is at odds with the UK stance.

Biden is also not keen; despite the "improve trade" stance he says he would need to see major changes before signing which, as I understand it, the CPTPP don't want because it's at odds with the provisions of the current agreement.
So still the USA would be at odds with the UK stance.

The CPTPP doesn't require the giving-up of any sovereignty; it does not demand access to territorial waters; and it does not require the UK to submit to any other judiciary.
It also does not require an annual payment of tens of billions of pounds for membership.

Now that Japan has agreed a UK deal and Canada declaring it will sign a UK deal by the year's end AND with the remaining CPTPP members ALL making positive noises regarding the UK joining, things look really promising for the UK.