Your turtle will need several upgrades in their life if you do a small tank to start. (Which was my mistake in turtle care) The best rule of thumb is 10 gallons water per inch of shell. Girls can grow 12 inches while males stay closer to 8- 10inches.
My old man is being moved from a glass aquarium into a "tuff stuff" 110 gallon feed tub that I am making into an indoor pond. The canister filter can be used with either setup but the local farm tractor store offers the black tub for $70 versus $100-200 for a new glass aquarium.
Resources and infographics to study up on turtle care are great on Resto aquatic turtle FB group. The people on there are very helpful and have charts for food requirements (as they need a diverse diet)and pictures of other peoples setup/ tank design/ lighting. There is alot to consider so I would suggest brushing up on info there to get a better idea.
Hope this helps!
Edit to add amazon links- Heater https://www.amazon.com/gp/product/B000IWXHMI/ref=ppx_yo_dt_b_asin_title_o04_s00?ie=UTF8&psc=1 Lamp https://www.amazon.com/gp/product/B07RL9JKKV/ref=ppx_yo_dt_b_asin_title_o05_s02?ie=UTF8&psc=1 Lamp Stand https://www.amazon.com/gp/product/B08374M6XY/ref=ppx_yo_dt_b_asin_title_o05_s00?ie=UTF8&psc=1 Basking Bulb https://www.amazon.com/gp/product/B0006L2UBK/ref=ppx_yo_dt_b_asin_title_o05_s01?ie=UTF8&th=1 UVB (this is a UVA and UVB and I have heard it is best to just do UVB but this is what I have had for a bit) https://www.amazon.com/gp/product/B00101JI2Y/ref=ppx_yo_dt_b_asin_title_o05_s01?ie=UTF8&psc=1 Small net to help keep tank clean https://www.amazon.com/gp/product/B06XNNY4YW/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1
1) My Turtle is 3 inches.
2) My Tank has 7 Gallons of water. ( I always put 7 gallons because i dont want him/her to drown)
3) My Tank Holds 20 Gallons (https://www.petco.com/shop/en/petcostore/product/aga-20g-30x12x12-lng-bk-tank-170933)
4) I Give My Turtle ReptoMin Baby Floating Food Sticks (https://www.amazon.com/dp/B00025670U?psc=1&ref=ppx_yo2ov_dt_b_product_details)
5) He/She Bask Like 2 to 6 Hours A Day. In the night He/She sleeps underwater like 6 to 8 hours
6) I use TetraFauna AquaSafe Reptile & Amphibian Water Conditioner for my Turtle water. (https://www.amazon.com/dp/B003JVR1OA?ref=ppx_yo2ov_dt_b_product_details&th=1)
7) The Basking lights i use are "E26/E27 Flexible Clamp Lamp Fixture" and "REPTI ZOO 15 W UVA UVB 5.0 Reptile Light"
(https://www.amazon.com/dp/B08QHM2JRM?psc=1&ref=ppx_yo2ov_dt_b_product_details)
(https://www.amazon.com/dp/B07CWMHBNX?psc=1&ref=ppx_yo2ov_dt_b_product_details)
8) The Filter for my Turtle is "hygger 150GPH Turtle Filter" (https://www.amazon.com/dp/B08PC318MN?psc=1&ref=ppx_yo2ov_dt_b_product_details)
9) My Turtle Heater is a "Tetra 26445 Fauna Aquatic Reptile Heater " (https://www.amazon.com/TetraFauna-Aquatic-Reptile-Heater-Turtles/dp/B000IWXHMI?pd_rd_w=N3LjK&content-id=amzn1.sym.bc622850-a717-4d94-96c3-7cc183488298&pf_rd_p=bc622850-a717-4d94-96c3-7cc183488298&pf_rd_r=D4GZ5KZZYB3KHZ645Z8B&pd_rd_wg=14z8S&pd_rd_r=38c4f671-d2be-4122-baa0-1e2991fd463b&pd_rd_i=B000IWXHMI&psc=1&ref_=pd_bap_d_rp_3_t)
10) I Change Her/His water every week and sometimes i do full change water every 2 weeks same as the filter.