Cannot answer on how it works in Sweden, but speaking taking out a residental loan in Denmark, the rules states that you are obliged to put down 15% (edit: at minimum as rules states) of the principal from your own pocket and obtain a loan for the 85% reminder, typically 80% as mortgage loan.
Here, however, there is a jumble of options that the various banks in Denmark offer, incl. party as bank loan and party as mortgage loan.
Quite logically, in terms of interest, it is of course worthwhile to make larger deposits with lower current interest rates, if you have the money.
You can always reschedule your loan, which costs a notable fee.
With the rising interest rates after the introduction of the Ukraine war, it has been worthwhile for many owners to do so, consequently shaving off a large part of the principal by rescheduling to a new loan with a higher interest rate, which you ultimately not notice in day-to-day life, as the new amortization model results in circa the same montly rate - well helped by the fact that you can deduct housing interest from housing taxation.
Edit:
And what is the advantage then?
If interest rates drops again, you will have shaved off a good part of your principal and you can convert again with great economical benefit.
However, this is something the banks in Denmark are quite reluctant to negotiate and demands detailed documentation of robust finances of your private economies and meddle in the details of how the money is used.
One could then say that the banks should just obey costumers wishes, but the reason is that in Denmark there are also a number of types of interest-free loans, which many have been caught in and are now left with very suspended finances, some have even had to sell their house in foreclosure. It is bad for the banks' finances, not to speak of the finances on a national level.
Myself I have a colleague who is caught up in it, and who now offers himself all kinds of extra shifts to get out of his cat pain
Fortunately, I have always had a rather difficult time with interest-free loans, and fortunately my wife has the same attitude, so we were able to shave off 33% of out principal in the blink of an eye by converting from 1% mortgage interests to 5%.
(The interest rate on offered mortgage loans even reached as low as 0.5% just before the war in Ukraine broke out, but here it was not worthwhile for us to convert from 1% to 0.5% as the conversion fee would've make out loan more expensive when everything is summed up).
Or the simple option, if you are a multi-millionaire like Jonas:
Just deposit the entire amount in cash as a one-off payment