Like Barca's all-time top goalscorer Messi, Yamal came through the club's feted La Masia youth academy and has often drawn comparisons to the Argentine forward, which he has tried to play down.
Yamal, 18, scored a brilliant acrobatic goal on Sunday as Barcelona beat Real Oviedo 3-0 to move top of LaLiga.
"I think Lamine has his path, and he knows it. Comparing any player playing now with Messi is crazy," Olmo told a news conference ahead of Barcelona's Champions League match against FC Copenhagen on Wednesday.
"Lamine is a 'spectacle', he is very young, what he's giving us now is incredible, and in the future it will be a lot more."
Yamal made his Barcelona debut at the age of 15 and has broken several records in his first seasons at the club, including becoming the youngest LaLiga goalscorer.
The winger lifted the EURO 2024 trophy with Spain and was vital in Barca's run to the Champions League semi-finals last season.
"(Yamal) is calm, he has his path and his idea. We will be there to help him, that's our job," added Olmo.
"It's a collective thing in the end. If Lamine plays well, wins, and scores goals, then the team will win."
Barcelona host Copenhagen on Wednesday, needing to win and hope other results go their way to seal a top-eight league phase spot to progress directly to the last 16.
The Spanish champions will be without injured midfielder Pedri Gonzalez as well as the suspended Frenkie de Jong, but Ferran Torres may return after injury, said coach Hansi Flick.
"We have to play this match and respect Copenhagen, they have a fantastic team, and play at a top level," said Flick.
"We have a big chance to finish in the (top) eight; we will do everything we can to reach it."
