Yea, Tee in to a horizontal length, or right angle it to a horixontal length.
You can buy the bends, or fabricate them using pop rivets. (best to ensure if you fabricate, that the trunking has one side continuous, eg, uncut. This ensures continuity).
If you buy bends, ensure you use atleast one earth link across the join, the trunking manufacturers make links to fit where theie screw holes are.
Paxoline is hard to get nowadays, and couplers with 2 bushes are a better job.
Dont forget to supp bond the trunking from the fuseboard
And use round head screws to fix the trunking home, not counter sunk
And, not many people seem to realise, if you cut the trunking lid, and the cut comes in a bad place, leaving the trunking lid buckles to far from the end.....you can get additional buckles that you can drill in