Ocean made a smaller brief with just a front liner. I believe it was called Ocean Speed. They had Ocean Champion and Ocean Pool as well for different styles in the nylon days.

Etsy has a size 28 Ocean Champion that looks over-sized now
https://www.etsy.com/listing/1783380...ion-mens-swim?

Auction site has a Lifeguard logo on one
https://www.ebay.com/itm/176281428744?

Oversized speedos were never a thing for me.
As I remember speedos were seen as similar to the brief style underwear all boys wore in the 1980's
They were meant to fit snuggly to provide support and free movement and were only intended to last a year or two.
I recieved a lot of hand me down clothes from my older brother growing up but never underwear or swimwear.
All my speedos were brand new and fit properly like lycra should.

That was interesting.
That style of high waisted brief was non existent by the 1970's (in Australia).
I guess it was a remanent from the post war period when showing skin below the naval was still considered a bit risque.
They probably went out of fashion a lot quicker in Europe and Australia.
I'd love to be able to by a reproduction made out of modern Lycra.

Girls gym knickers were that shape in the 1960s.