After the Coutinho and Dembele debacle one thing is for sure. They need a forward who's great at making runs off the ball. We can only afford one player that need the ball and that's Messi.
Look at Liverpool. All of their forwards work hard off the ball, are constantly making runs behind making it easier for their midfielders to play a pass over the top or split defenders if they're able to.
That is true, but there is another area that need to be looked at when we go for a striker. The ability to operate with his back to the goal. To make passes and plays when he receives the ball with defender on his back and make something for it.
Suarez is/was brilliant at it, one of the main reasons he is great fit for Messi. Benzema is also great at that and this was influential in his career, Higuain too made life easier for everyone with it (until he misses chances in the finals) and even in your example; the liverpool trio Firmino is good at that aspect, making life easier for Mane & Salah.
I didn't watch Lautaro that much, from what I've watched he isn't that player. But if you watch him more you can tell me if he has that ability to`r not. Because it is one of those underrated aspects that could be the make or break for players.
How about an RB worthy of playing for us?
We have so many needs, and that is why I am against getting Lautaro.
Don't think we need 110M player anymore, although we surely need a guy who can get us 20-30 goals per season.