Do you believe in multiple dimensions and, if so, do you believe inter-dimensional travel is possible?

I'm on the fence. Someday in the far future this question will be answered

Kaluza and Klein theorized a fifth dimension in 1921 to unify gravity with electromagnetic force, as a means toward trying to find the Universal Field Theory.
Klein thought the fifth dimension would be rolled up into a tiny, compact loop of one 33 billionth of a centimetre, hence too small to be detected.

I somehow think it would be rather tricky to travel in this dimension.

Yes, I believe there's a strong possibility of multiple dimensions existing, although I don't think we understand them enough, or even know if they really exist, to know whether or not we can travel to them.

Seems you are talking of time travel.
Theoretically it seems possible.
Practically I don’t think it has happened as in people from the future visiting now.

I know that time and space is the 4 th dimension, is in the current physical realm we are in the third.

I guess theoretically multiple dimensions are possible. As for travel, I don't know.

there are at least three dimensions.

no.

No