Poems in different periods have different rhymes. The ancients had to learn rhyme, and the poets of the Tang Dynasty naturally had to learn rhyme of the Tang Dynasty. With the change of language and times, not many people knew ancient rhyme in Ming and Qing dynasties, so it is necessary to look up books when writing ancient poems. Scholars in Qing Dynasty had special phonology to collate rhymes.
The simplest meter is the staggered use of flat tones. For example, the rhythm of a five-character poem is:
Even, even,
Flat and faint;
Flat and faint,
It is flat.
These all need training. If you write too much, you will naturally remember it.