Let's just look at Kohli's semi and final contributions at World Cups, when it really matters
2011 semi (in IND) vs PAK : 9 off 21 balls
2011 final (in IND) vs SRL : 35 off 49 balls
2015 semi (in AUS) vs AUS : 1 off 13 balls
2019 semi (in ENG) vs NZL : 1 off 6 balls
2023 semi (in IND) vs NZL : 117 off 113 balls
2023 final (in IND) vs AUS : 54 off 63 balls
so 217 runs in semis and finals, average 36.17 and SR 81.89. In India, which is both semi and final combos 215 runs, average 53.75 and SR 87.40. Fact remains though 1 win in 4 World Cups, wasn't a major factor in the 2011 win as he was out at 114/3 so a lot of work which Dhon(k)i did with 91no, not to say he didn't help but he is supposed to be some kind of GOAT not just part of a herd.
had a quick look for Champions Trophy
2013 semi (in ENG) vs SRL : 58no off 64 balls
2013 final (in ENG) vs ENG : 43 off 34 balls*
2017 semi (in ENG) vs BAN : 96no off 78 balls
2017 final (in ENG) vs PAK : 5 off 9 balls
*reduced to 20 overs a side
better record in England in Champions Trophy semis and final although Sri Lanka and Bangladesh are hardly world beaters, no Murali in 2013, Malinga 8-0-54-0 their main weapon nullified if you want one perspective, ineffectual from the opposite. You can easily argue Bangladesh must have done something right to be in a semi, same with deshis, but looking at the table England won all 3 of their games, neither Australia nor New Zealand won with both suffering an NR (aussies 2) so deshis beat kiwis and that was enough
Sri Lanka beat aussies by 20 runs in 2013, England by 7 wickets which is some feat by England who didn't have a great bowling attack, Bresnan 0/63 in that game, Bopara and Root 9-0-60-0 the ill judged fifth bowler and Broad spanked for 0/67 off his 8.1 as Sangakkara hit 134no off 135 balls and three others made 42+