illegal claim

You cannot make an illegal move online.
Over the board it depends if an arbiter is observing the game or not.
As long as you have not made your move you can claim an illegal move.
For the first illegal move the position is corrected and you get 2 extra minutes of time.
For the second illegal move you win the game.
Rules on this are the same for Blitz and Rapid.

B.3    Otherwise, play shall be governed by the Rapid chess Laws as in Article A.2, A.3 and A.5.

A.5.2    If the arbiter observes an action taken under Article 7.5.1, 7.5.2, 7.5.3 or 7.5.4, he/she shall act according to Article 7.5.5, provided the opponent has not made his/her next move.
If the arbiter does not intervene, the opponent is entitled to claim, provided the opponent has not made his/her next move. If the opponent does not claim and the arbiter does not intervene, the illegal move shall stand and the game shall continue.
Once the opponent has made his/her next move, an illegal move cannot be corrected unless this is agreed by the players without intervention of the arbiter.

7.5     Illegal moves:

7.5.1    An illegal move is completed once the player has pressed his/her clock.
If during a game it is found that an illegal move has been completed, the position immediately before the irregularity shall be reinstated.
If the position immediately before the irregularity cannot be determined, the game shall continue from the last identifiable position prior to the irregularity.
Articles 4.3 and 4.7 apply to the move replacing the illegal move.
The game shall then continue from this reinstated position.

7.5.2    If the player has moved a pawn to the furthest distant rank, pressed the clock, but not replaced the pawn with a new piece, the move is illegal.
The pawn shall be replaced by a queen of the same colour as the pawn.

7.5.3    If the player presses the clock without making a move,
it shall be considered and penalised as if an illegal move.

7.5.4    If a player uses two hands to make a single move
(for example in case of castling, capturing or promotion) and pressed the clock,
it shall be considered and penalised as if an illegal move.

7.5.5    After the action taken under Article 7.5.1, 7.5.2, 7.5.3 or 7.5.4 for the first completed illegal move by a player, the arbiter shall give two minutes extra time to his/her opponent;
for the second completed illegal move by the same player the arbiter shall declare the game lost by this player. However, the game is drawn if the position is such that the opponent cannot checkmate the player’s king by any possible series of legal moves.

https://handbook.fide.com/chapter/E012023