What part of the question do you not understand????
I don't know which election you mean here.It takes votes away from Trump.
I know in the UK third parties work differently, but the most usage third parties have in America aside from making a statement is just stealing votes from either the Democrats or Republicans. Like Perot was more conservative, right? Therefore he took more votes from Bush, giving Clinton a major advantage.
If you mean in the 2020 election, again, it doesn't matter if the votes are being taken away from Trump as he has no chance of winning in your area anyway. Not very different to what would happen in a British constituency:
Results of a by-election in Ringlington-upon-Gent
SANDERS, Bernie Labour Party - 40,086 votes
TRUMP, Donald British National Party - 6,871 votes
JOHNSON, Gary Monster Raving Loony Party - 4,946 votes
Voting for Gary Johnson as your MP in this hypothetical constituency wouldn't take votes away from Trump, as Sanders is guaranteed to be MP anyway.
If you mean the 2024 election, Trump won't be running in that. The Republicans could very well nominate an anti-nuclear candidate. Or, both parties could nominate pro-nuclear candidates. As well as that, there isn't really any reason to believe that Johnson would take any more votes away from a Republican than he would from a Democrat. He'd just be taking votes from fiscally conservative Democrat voters and socially progressive Republican voters.
Also, I don't know whether Perot was more conservative, but I don't know enough about him. Regardless, exit polls show that he took votes evenly from Clinton and Bush (like Johnson likely would with the Democrat and the Republican in 2024), and in the states where he did best, Bush still won. This was not a major factor leading to Bush losing in the slightest.