Uneven gap between two different floors
As noted above you should be able to find a wooden transition piece that would be large enough. The box stores may not carry such a large piece in stock but I'd be surprised if you couldn't find one online somewhere.

Another option is to make a wooden transition piece yourself by taking something a 1x4 board and beveling the edges using a table saw, then sanding and finishing the piece. This would require some amount of skill, but it's a pretty simple job.

Other possible options:

1) fill it in with sanded grout that matches the grout in the existing tile floor. It won't look amazing, and the grout may crack over time especially if the vinyl floor expands into it and/or the subfloor is not great. But it's a quick, cheap and easy fix that will probably last until you are ready to redo the tile floor.

2) Get a matching piece of the vinyl flooring and cut it to fit the gap. This might look a little odd, but not too odd.

3) Fill it in with floor putty. They sell it in different colors. A gap that large filled with putty might also look a little odd, but it would be quick and easy to apply, and it should hold up well.

A final thought: You could always use a smaller transition piece that you buy off the shelf to cover most of the gap, then fill in the rest with floor putty or grout.