That's rather how a government is elected than the form it should take.
For instance one could say the US and the UK both have elections that are essentially FPTP but their forms of government are radically different.
I disagree. If you look at how different PR parliaments are compared to FPTP parliaments.
Let's take a look.
FPTP
USA - two political parties who gained 98.4% of the vote in the 2022 House, and 98.1% of the vote in the 2022 Senate race.
UK - 10 political parties. Four of which are from Northern Ireland and only run in Northern Ireland where other political parties don't bother. The SNP, Scottish Nationalist Party, Plaid Cymru, Welsh Nationalist Party, the Green Party which wins in Brighton Pavilion (Brighton is the UK's answer to San Francisco, gay center of the country) and essentially it's the Caroline Lucas show, without her they might not win.
Then on top of these nationalist parties (6 of them) and the Green Party that wins in only one place, there are three main parties.
One is the Conservatives. Equivalent of the Republicans.
Two are the Lib Dems and Labour, essentially the equivalent of the Democrats.
And they cancel each other out to let the Tories win most of the time. Literally the two of them gained less than 1,000 votes less than the Tories combined, but got 150 less seats.
So essentially there's a Dem v. Rep thing going on in the UK with nationalist parties and a green version of Bernie Sanders. It's a two horse race, with one horse crippled (the left).
PR
Germany - 7 parties. Traditional left, traditional right, further left, further right, green left, center right and a local party, normally 6 parties (due to a 5% cut off)
Denmark - 10 parties. A social democratic party, an agrarian left-right party, a right wing populist party, a social liberal party, a socialist party, and eco-socialist party, a conservative party, a green party, a nationalistic right wing party and a center liberal party.
PR leads to a completely different make up of political parties, of politics of everything. The form is totally different.
FPTP will lead to two strong parties and not much else. PR will lead to two main parties CDU/CSU and SPD in Germany, Social Democrats and Venstre in Denmark, but with many other parties and the main parties needing to be more sensible and listen more to the people and having to cut deals with smaller parties.