Previous keepers or the current ones?I think they don’t look that tall with the size of modern players
Many positions now have giants in them, not every player of course, but there is height in every team now. A bit like the discussion of comparing players from different eras in terms of skill, pace etc, we probably can't compare in term of height either on the whole. Food availability from birth, diet etc, means you are not comparing like with like (rugby is the biggest example of this)
I do also think that tv makes someone look much bigger. I've stood next to many footballers in different situations and none of them look the size that they do on tv. Shearer is one that stands out up here, or doesn't stand out as it happens. Same with golfers when you see them live at a tournament. Scottie Scheffler looked much slighter than I expected at the Scottish Open.