Is there track that you can run standard gauge and gauge 1. On the same track

Standard gauge is 2.125" (two and an eighth) and G-gauge is 1.75" (one and three-quarters). Are you asking is anyone makes a combination type track that can accept either gauge? I am not aware of that type of track.  It might be possible to make it yourself by hand-laying a fourth rail just inside of one of the outer standard-gauge rails for use by the G trains, but it would be a complicated task to create switches. The extra rail would have to be insulated at every tie, to provide the correct (isolated) electrical path for the 2-rail G trains. There would also be another issue, and that is: would the flanges on the G trains work on the (one) outside standard gauge rail.