Tuchel has achieved good things in Chelsea and I think he will be supported in the club and I don't think he would like to have Ronaldo. Problem with Ronaldo is he only can contribute goals and mentality. In modern football, coaches and teams need more than goals from strikers. They must contribute more for defense in general. Strikers and attacking players are first defense fence to reduce pressure on midfielders and protect defense system.
Strength should be evenly distributed in all areas of the field and it would be great if all the players supported each other to make the team stronger and more impressive. A good defense will save the team from losing and conceding more goals. That's what every team expects, but maybe it won't be very good if they don't have a good striker.
Chelsea have been quite active in the transfer market so far and they appear to be much busier than other teams when it comes to transfers. Several players have been recruited but they still haven't finished the pursuit of other players in the market. So maybe it's true, Chelsea are a good title contender this season after Manchester City and Liverpool.