Free Play is a mode in all 4 games (Flow Free App, Flow Free: Bridges, Flow Free: Hexes & Flow Free: Warps). It is the normal mode in which offers a wide variety of packs and levels along with daily levels to play in. Unlike in Time Trial, there is no time limit, but there are finite levels. Without the access to this mode, there wouldn't be much purpose to play these games, other than just playing the Time Trial mode.
As packs and levels are finite (unlike in Time Trial mode), there is definitely a certain end for all 4 games so that they are completed. However, it is not completely truly the case, because of Daily Puzzles. One can complete every single level in every single pack and earn achievements in doing so, whether they finish it perfectly or not, but there will always be new levels coming up in all 4 games everyday for those who finished the rest of the levels.
Free Play • Time Trial