On chess.com, im pretty sure they all go through
what happens

Yes, players equal on tiebreak will both advance (or all advance, in the case of 3 players). The same thing happens when only one player is supposed to advance.

There isn't a second tie-breaking system. If more people advance than was originally expected, the number of groups in the next round can be adjusted to fit the new total number of players. Suppose you start with 8 groups in Round 1 and the rules say 1 person advances from each group. The TD's original plan is for Round 2 to have 8 people divided into 2 groups of 4 each. If there's a tie in Round 1 that results in 9 people advancing to Round 2 instead of 8, the TD could rearrange Round 2 to be 3 groups of 3 players each.
If the number of advanced players can't be divided into reasonable equal groups, there's nothing requiring the groups to have equal numbers of players. I'm in Round 2 of a tournament that advanced 8 players out of Round 1, but one of them must have dropped out or something, because now we have only 7 players in Round 2. For Round 2 we have 3 players in Group 1 and 4 players in Group 2.
hi,
what happens in a tournament if the score and tie break is equal for three players while 2 are going to the next stage??