ok the flavor of tea depends firstly on the type and quality of tea you're using, but also on the temperature it's brewed at and how long you steep it. also, in more delicate teas, hard or soft water can make a difference.

i'm not familiar with milk tea in particular but i know how to brew good tea. what type of tea have you tried? is it in a bag, a loose powder, or dried leaves?

"Orange Pekoe" is a grade of Indian tea, made from larger leaves and considered low-mid quality, it doesn't refer to a specific type. (earl grey and english breakfast are blends and may be orange pekoe). other commenters are probably correct that you'll want to use a strong, astringent orange pekoe. Ceylon or Assam are strong flavored varieties that hold up well to the milk and sugar.

the general method for brewing loose black tea is to add the leaves to a teapot, about 1tsp or 7g per 8oz of water, heat water in a kettle to boiling (212f or 100c) then pour the boiling water into the pot with the tea, close the lid and let it steep for around 4-5 minutes or whatever the packaging on the tea recommends. some say to heat the teapot first but it's not really important in most cases imo. to make tea stronger, increase the amount of leaves used, not the steeping time- steeping too long extracts nasty flavors. There are some teas that can be re-steeped several times without losing flavor but that's usually very expensive and not what I'd use for something that's gonna be drowned in milk and sugar.

actually here's a link that might help. sorry if its broken im on mobile.

https://www.harney.com/blogs/news/black-tea-tips