When I bought this, it looked like lotus (short and wide). But, after 2 weeks, it raised and became taller. I water it every week. What did I do wrong?

Probably trying to reach for more light

And watering it every week will eventually rot it.

Welcome to the Forum!
Your plant is a small succulent that needs very different conditions to live and grow well.
From your photo and the plant's condition, I would say it needs more light, different soil and pot, and different watering.
It does look like it complements the décor nicely, but plants are living things that need a certain environment to keep them growing indoors.

@Plant_Noobs,
Welcome to NGA!

I agree with the previous comments.

The plant expanded taller because the light level in its current spot is much lower than where it was previously growing. It was in very bright light, perhaps even outdoors in full sun. If you can place the plant in bright light, this shoot will not "shrink" back to the previous tighter growth, but it will eventually grow new shoots and those will be tighter rosettes if in bright enough light.

Is the container a bowl with no hole for drainage? Succulents like this need to be in pots with drain holes to keep water from pooling. The potting mix looks like a dense black peat. Succulents prefer a looser mix with some gritty aerating material such as perlite. As others said, the main hazard of being too wet is that the plant may develop rot and die. Allow the soil of succulents such as this one to become completely dry to the touch before watering again. Any excess water needs to drain away so the soil isn't soggy. It might be ok in the current medium if it's allowed to dry out between waterings.

Best wishes for success!

Pat

Hi & welcome!

Your plant looks like a Sempervivum to me. They have a reputation for not doing well inside over winter because the air is so warm. If you can put it right next to a window facing south, it might stay a little cooler at night and would enjoy the extra light either way.
Info in the plant database on this site:
The Sempervivum Database
More pics to compare to your plant:
Sempervivum

You might have an interest in a similar looking plant that can stay looking great in a lot less light:
Haworthiopsis attenuata var. radula

Thank you so much all for your kind reply and suggestion! All of you are very helpful! I'll change the pot and put the plant near windows to get better light exposure. May I know how should I water this kind of plants?

A south window is best, west being second. I'd say water when dry.

Looks like a sempervivum gone awry with too little light to me also. I do sympathize with anyone newer to the plant world: what the heck does "water when dry mean"? Dry to the bottom or just the surface? IMO in this case, water when you think half the soil is bone dry.

The leaves will become softer when it is in strong need of water. That's OK, but it is an indication that you can water more for best growth.